21147397920 has 192 divisors, whose sum is σ = 80744791680. Its totient is φ = 5126630400.

The previous prime is 21147397919. The next prime is 21147397927. The reversal of 21147397920 is 2979374112.

21147397920 is a `hidden beast` number, since 2 + 1 + 1 + 473 + 97 + 92 + 0 = 666.

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

It is not an unprimeable number, because it can be changed into a prime (21147397927) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 174991 + ... + 270030.

It is an arithmetic number, because the mean of its divisors is an integer number (420545790).

Almost surely, 2^21147397920 is an apocalyptic number.

21147397920 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21147397920 is an abundant number, since it is smaller than the sum of its proper divisors (59597393760).

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

21147397920 is a wasteful number, since it uses less digits than its factorization.

21147397920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 445056 (or 445042 counting only the distinct ones).

The product of its (nonzero) digits is 190512, while the sum is 45.

The spelling of 21147397920 in words is "twenty-one billion, one hundred forty-seven million, three hundred ninety-seven thousand, nine hundred twenty".