21075876864 has 528 divisors, whose sum is σ = 74375861760. Its totient is φ = 5875752960.

The previous prime is 21075876859. The next prime is 21075876883. The reversal of 21075876864 is 46867857012.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a self number, because there is not a number n which added to its sum of digits gives 21075876864.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 63673179 + ... + 63673509.

Almost surely, 2^21075876864 is an apocalyptic number.

21075876864 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21075876864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37187930880).

21075876864 is an abundant number, since it is smaller than the sum of its proper divisors (53299984896).

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

21075876864 is a wasteful number, since it uses less digits than its factorization.

21075876864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 421 (or 390 counting only the distinct ones).

The product of its (nonzero) digits is 4515840, while the sum is 54.

The spelling of 21075876864 in words is "twenty-one billion, seventy-five million, eight hundred seventy-six thousand, eight hundred sixty-four".