21543621720 has 64 divisors (see below), whose sum is σ = 64643171040. Its totient is φ = 5743872000.

The previous prime is 21543621707. The next prime is 21543621763. The reversal of 21543621720 is 2712634512.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 763870 + ... + 791570.

Almost surely, 2^21543621720 is an apocalyptic number.

21543621720 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21543621720 is an abundant number, since it is smaller than the sum of its proper divisors (43099549320).

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

21543621720 is a wasteful number, since it uses less digits than its factorization.

21543621720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34196 (or 34192 counting only the distinct ones).

The product of its (nonzero) digits is 20160, while the sum is 33.

The spelling of 21543621720 in words is "twenty-one billion, five hundred forty-three million, six hundred twenty-one thousand, seven hundred twenty".