21392490 has 32 divisors (see below), whose sum is σ = 58677120. Its totient is φ = 4889664.

The previous prime is 21392467. The next prime is 21392491. The reversal of 21392490 is 9429312.

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

It is not an unprimeable number, because it can be changed into a prime (21392491) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 50725 + ... + 51144.

It is an arithmetic number, because the mean of its divisors is an integer number (1833660).

Almost surely, 2^21392490 is an apocalyptic number.

21392490 is an abundant number, since it is smaller than the sum of its proper divisors (37284630).

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

21392490 is a wasteful number, since it uses less digits than its factorization.

21392490 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 101886.

The product of its (nonzero) digits is 3888, while the sum is 30.

The square root of 21392490 is about 4625.2016172271. The cubic root of 21392490 is about 277.6006290352.

The spelling of 21392490 in words is "twenty-one million, three hundred ninety-two thousand, four hundred ninety".