21211164 has 72 divisors (see below), whose sum is σ = 58767072. Its totient is φ = 6410880.

The previous prime is 21211139. The next prime is 21211181. The reversal of 21211164 is 46111212.

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.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 28177 + ... + 28919.

Almost surely, 2^21211164 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 21211164, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29383536).

21211164 is an abundant number, since it is smaller than the sum of its proper divisors (37555908).

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

21211164 is a wasteful number, since it uses less digits than its factorization.

21211164 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 827 (or 822 counting only the distinct ones).

The product of its digits is 96, while the sum is 18.

The square root of 21211164 is about 4605.5579466553. The cubic root of 21211164 is about 276.8140741226.

Adding to 21211164 its reverse (46111212), we get a palindrome (67322376).

The spelling of 21211164 in words is "twenty-one million, two hundred eleven thousand, one hundred sixty-four".