21137490 has 96 divisors (see below), whose sum is σ = 62052480. Its totient is φ = 5116320.

The previous prime is 21137489. The next prime is 21137497. The reversal of 21137490 is 9473112.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (21137497) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 32347 + ... + 32993.

It is an arithmetic number, because the mean of its divisors is an integer number (646380).

Almost surely, 2^21137490 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21137490, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31026240).

21137490 is an abundant number, since it is smaller than the sum of its proper divisors (40914990).

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

21137490 is a wasteful number, since it uses less digits than its factorization.

21137490 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 685 (or 668 counting only the distinct ones).

The product of its (nonzero) digits is 1512, while the sum is 27.

The square root of 21137490 is about 4597.5526098132. The cubic root of 21137490 is about 276.4932107373.

The spelling of 21137490 in words is "twenty-one million, one hundred thirty-seven thousand, four hundred ninety".