21587878280 has 64 divisors (see below), whose sum is σ = 51829718400. Its totient is φ = 8068584960.

The previous prime is 21587878271. The next prime is 21587878289. The reversal of 21587878280 is 8287878512.

It is an interprime number because it is at equal distance from previous prime (21587878271) and next prime (21587878289).

It is not an unprimeable number, because it can be changed into a prime (21587878289) 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, 139076 + ... + 250035.

It is an arithmetic number, because the mean of its divisors is an integer number (809839350).

Almost surely, 2^21587878280 is an apocalyptic number.

21587878280 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21587878280 is an abundant number, since it is smaller than the sum of its proper divisors (30241840120).

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

21587878280 is a wasteful number, since it uses less digits than its factorization.

21587878280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 389214 (or 389210 counting only the distinct ones).

The product of its (nonzero) digits is 4014080, while the sum is 56.

The spelling of 21587878280 in words is "twenty-one billion, five hundred eighty-seven million, eight hundred seventy-eight thousand, two hundred eighty".