21897582438 has 16 divisors (see below), whose sum is σ = 43797370176. Its totient is φ = 7298826600.

The previous prime is 21897582431. The next prime is 21897582439. The reversal of 21897582438 is 83428579812.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21897582431) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 55345 + ... + 216467.

It is an arithmetic number, because the mean of its divisors is an integer number (2737335636).

Almost surely, 2^21897582438 is an apocalyptic number.

21897582438 is an abundant number, since it is smaller than the sum of its proper divisors (21899787738).

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

21897582438 is a wasteful number, since it uses less digits than its factorization.

21897582438 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 183779.

The product of its digits is 7741440, while the sum is 57.

The spelling of 21897582438 in words is "twenty-one billion, eight hundred ninety-seven million, five hundred eighty-two thousand, four hundred thirty-eight".