21247153920 has 216 divisors, whose sum is σ = 76049064000. Its totient is φ = 5470445568.

The previous prime is 21247153903. The next prime is 21247153951. The reversal of 21247153920 is 2935174212.

21247153920 is a `hidden beast` number, since 21 + 247 + 1 + 5 + 392 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 302281 + ... + 365879.

It is an arithmetic number, because the mean of its divisors is an integer number (352079000).

Almost surely, 2^21247153920 is an apocalyptic number.

21247153920 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 21247153920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38024532000).

21247153920 is an abundant number, since it is smaller than the sum of its proper divisors (54801910080).

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

21247153920 is a wasteful number, since it uses less digits than its factorization.

21247153920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 63655 (or 63638 counting only the distinct ones).

The product of its (nonzero) digits is 30240, while the sum is 36.

The spelling of 21247153920 in words is "twenty-one billion, two hundred forty-seven million, one hundred fifty-three thousand, nine hundred twenty".