21085978320 has 200 divisors, whose sum is σ = 79892699040. Its totient is φ = 5111735040.

The previous prime is 21085978307. The next prime is 21085978349. The reversal of 21085978320 is 2387958012.

It is a happy number.

21085978320 is a `hidden beast` number, since 21 + 0 + 8 + 597 + 8 + 32 + 0 = 666.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 76630 + ... + 219189.

Almost surely, 2^21085978320 is an apocalyptic number.

21085978320 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21085978320 is an abundant number, since it is smaller than the sum of its proper divisors (58806720720).

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

21085978320 is a wasteful number, since it uses less digits than its factorization.

21085978320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 295855 (or 295840 counting only the distinct ones).

The product of its (nonzero) digits is 241920, while the sum is 45.

The spelling of 21085978320 in words is "twenty-one billion, eighty-five million, nine hundred seventy-eight thousand, three hundred twenty".