21578462640 has 640 divisors, whose sum is σ = 92336947200. Its totient is φ = 4520033280.

The previous prime is 21578462603. The next prime is 21578462657. The reversal of 21578462640 is 4626487512.

21578462640 is a `hidden beast` number, since 2 + 15 + 7 + 8 + 4 + 626 + 4 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 8904469 + ... + 8906891.

It is an arithmetic number, because the mean of its divisors is an integer number (144276480).

Almost surely, 2^21578462640 is an apocalyptic number.

21578462640 is a gapful number since it is divisible by the number (20) 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 21578462640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (46168473600).

21578462640 is an abundant number, since it is smaller than the sum of its proper divisors (70758484560).

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

21578462640 is a wasteful number, since it uses less digits than its factorization.

21578462640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2502 (or 2490 counting only the distinct ones).

The product of its (nonzero) digits is 645120, while the sum is 45.

The spelling of 21578462640 in words is "twenty-one billion, five hundred seventy-eight million, four hundred sixty-two thousand, six hundred forty".