21499534638 has 24 divisors (see below), whose sum is σ = 47034584688. Its totient is φ = 7096933152.

The previous prime is 21499534591. The next prime is 21499534649. The reversal of 21499534638 is 83643599412.

21499534638 is a `hidden beast` number, since 2 + 1 + 49 + 9 + 534 + 63 + 8 = 666.

It is a congruent number.

It is an unprimeable number.

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 11 ways as a sum of consecutive naturals, for example, 5796295 + ... + 5800002.

It is an arithmetic number, because the mean of its divisors is an integer number (1959774362).

Almost surely, 2^21499534638 is an apocalyptic number.

21499534638 is an abundant number, since it is smaller than the sum of its proper divisors (25535050050).

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

21499534638 is a wasteful number, since it uses less digits than its factorization.

21499534638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11596408 (or 11596405 counting only the distinct ones).

The product of its digits is 5598720, while the sum is 54.

The spelling of 21499534638 in words is "twenty-one billion, four hundred ninety-nine million, five hundred thirty-four thousand, six hundred thirty-eight".