21373590 has 64 divisors (see below), whose sum is σ = 62083584. Its totient is φ = 4597248.

The previous prime is 21373589. The next prime is 21373591. The reversal of 21373590 is 9537312.

It is an interprime number because it is at equal distance from previous prime (21373589) and next prime (21373591).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21373591) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 577 + ... + 6563.

It is an arithmetic number, because the mean of its divisors is an integer number (970056).

Almost surely, 2^21373590 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21373590, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31041792).

21373590 is an abundant number, since it is smaller than the sum of its proper divisors (40709994).

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

21373590 is a wasteful number, since it uses less digits than its factorization.

21373590 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6021.

The product of its (nonzero) digits is 5670, while the sum is 30.

The square root of 21373590 is about 4623.1580115761. The cubic root of 21373590 is about 277.5188527083.

The spelling of 21373590 in words is "twenty-one million, three hundred seventy-three thousand, five hundred ninety".