21981594 has 64 divisors (see below), whose sum is σ = 49104000. Its totient is φ = 6531840.

The previous prime is 21981593. The next prime is 21981601. The reversal of 21981594 is 49518912.

It is not an unprimeable number, because it can be changed into a prime (21981593) 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, 201612 + ... + 201720.

It is an arithmetic number, because the mean of its divisors is an integer number (767250).

Almost surely, 2^21981594 is an apocalyptic number.

21981594 is an abundant number, since it is smaller than the sum of its proper divisors (27122406).

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

21981594 is a wasteful number, since it uses less digits than its factorization.

21981594 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 223.

The product of its digits is 25920, while the sum is 39.

The square root of 21981594 is about 4688.4532630709. The cubic root of 21981594 is about 280.1257683298.

The spelling of 21981594 in words is "twenty-one million, nine hundred eighty-one thousand, five hundred ninety-four".