21525042 has 32 divisors (see below), whose sum is σ = 53673984. Its totient is φ = 5590800.

The previous prime is 21525017. The next prime is 21525059. The reversal of 21525042 is 24052512.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 22834 + ... + 23757.

It is an arithmetic number, because the mean of its divisors is an integer number (1677312).

Almost surely, 2^21525042 is an apocalyptic number.

21525042 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

21525042 is an abundant number, since it is smaller than the sum of its proper divisors (32148942).

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

21525042 is a wasteful number, since it uses less digits than its factorization.

21525042 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 46614.

The product of its (nonzero) digits is 800, while the sum is 21.

The square root of 21525042 is about 4639.5088102083. The cubic root of 21525042 is about 278.1728045926.

Adding to 21525042 its reverse (24052512), we get a palindrome (45577554).

The spelling of 21525042 in words is "twenty-one million, five hundred twenty-five thousand, forty-two".