21217620384 has 48 divisors (see below), whose sum is σ = 61884728640. Its totient is φ = 7072539840.

The previous prime is 21217620371. The next prime is 21217620409. The reversal of 21217620384 is 48302671212.

It is a happy number.

21217620384 is a `hidden beast` number, since 2 + 1 + 21 + 7 + 620 + 3 + 8 + 4 = 666.

It is a tau number, because it is divible by the number of its divisors (48).

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

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

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12277852 + ... + 12279579.

It is an arithmetic number, because the mean of its divisors is an integer number (1289265180).

Almost surely, 2^21217620384 is an apocalyptic number.

21217620384 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21217620384 is an abundant number, since it is smaller than the sum of its proper divisors (40667108256).

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

21217620384 is a wasteful number, since it uses less digits than its factorization.

21217620384 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24557450 (or 24557436 counting only the distinct ones).

The product of its (nonzero) digits is 32256, while the sum is 36.

It can be divided in two parts, 21217 and 620384, that added together give a square (641601 = 801²).

The spelling of 21217620384 in words is "twenty-one billion, two hundred seventeen million, six hundred twenty thousand, three hundred eighty-four".