21311136 has 216 divisors, whose sum is σ = 78073632. Its totient is φ = 5356800.

The previous prime is 21311123. The next prime is 21311137. The reversal of 21311136 is 63111312.

It is a super-2 number, since 2×21311136² = 908329035220992, which contains 22 as substring.

It is a hoax number, since the sum of its digits (18) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a nude number because it is divisible by every one of its digits.

Its product of digits (108) is a multiple of the sum of its prime divisors (54).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21311137) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 687441 + ... + 687471.

It is an arithmetic number, because the mean of its divisors is an integer number (361452).

Almost surely, 2^21311136 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21311136, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39036816).

21311136 is an abundant number, since it is smaller than the sum of its proper divisors (56762496).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21311136 is a wasteful number, since it uses less digits than its factorization.

21311136 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 96 (or 54 counting only the distinct ones).

The product of its digits is 108, while the sum is 18.

The square root of 21311136 is about 4616.3985963086. The cubic root of 21311136 is about 277.2482840375.

Adding to 21311136 its reverse (63111312), we get a palindrome (84422448).

The spelling of 21311136 in words is "twenty-one million, three hundred eleven thousand, one hundred thirty-six".