21500136 has 96 divisors (see below), whose sum is σ = 68889600. Its totient is φ = 5927040.

The previous prime is 21500111. The next prime is 21500137. The reversal of 21500136 is 63100512.

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

It is not an unprimeable number, because it can be changed into a prime (21500137) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 13881 + ... + 15351.

It is an arithmetic number, because the mean of its divisors is an integer number (717600).

Almost surely, 2^21500136 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 21500136, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34444800).

21500136 is an abundant number, since it is smaller than the sum of its proper divisors (47389464).

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

21500136 is a wasteful number, since it uses less digits than its factorization.

21500136 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1519 (or 1512 counting only the distinct ones).

The product of its (nonzero) digits is 180, while the sum is 18.

The square root of 21500136 is about 4636.8239129818. The cubic root of 21500136 is about 278.0654746322.

Adding to 21500136 its reverse (63100512), we get a palindrome (84600648).

The spelling of 21500136 in words is "twenty-one million, five hundred thousand, one hundred thirty-six".