20747233521 has 63 divisors (see below), whose sum is σ = 36797719881. Its totient is φ = 11231585064.

The previous prime is 20747233501. The next prime is 20747233543. The reversal of 20747233521 is 12533274702.

The square root of 20747233521 is 144039.

It is a perfect power (a square), and thus also a powerful number.

It is a tau number, because it is divible by the number of its divisors (63).

It is not a de Polignac number, because 20747233521 - 2⁵ = 20747233489 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20747233501) by changing a digit.

It is a polite number, since it can be written in 62 ways as a sum of consecutive naturals, for example, 1091959650 + ... + 1091959668.

Almost surely, 2^20747233521 is an apocalyptic number.

20747233521 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

20747233521 is the 144039-th square number.

20747233521 is the 72020-th centered octagonal number.

It is an amenable number.

20747233521 is a deficient number, since it is larger than the sum of its proper divisors (16050486360).

20747233521 is an frugal number, since it uses more digits than its factorization.

20747233521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 134 (or 29 counting only the distinct ones).

The product of its (nonzero) digits is 70560, while the sum is 36.

Multiplying 20747233521 by its sum of digits (36), we get a square (746900406756 = 864234²).

The spelling of 20747233521 in words is "twenty billion, seven hundred forty-seven million, two hundred thirty-three thousand, five hundred twenty-one".