20124545909521 has 9 divisors (see below), whose sum is σ = 20842559810683. Its totient is φ = 19430470441480.

The previous prime is 20124545909513. The next prime is 20124545909539. The reversal of 20124545909521 is 12590954542102.

The square root of 20124545909521 is 4486039.

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

It can be written as a sum of positive squares in only one way, i.e., 10552823717121 + 9571722192400 = 3248511^2 + 3093820^2 .

It is not a de Polignac number, because 20124545909521 - 2³ = 20124545909513 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20124545900521) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 130017786 + ... + 130172476.

Almost surely, 2^{20124545909521} is an apocalyptic number.

20124545909521 is the 4486039-th square number.

20124545909521 is the 2243020-th centered octagonal number.

It is an amenable number.

20124545909521 is a deficient number, since it is larger than the sum of its proper divisors (718013901162).

20124545909521 is an frugal number, since it uses more digits than its factorization.

20124545909521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 309440 (or 154720 counting only the distinct ones).

The product of its (nonzero) digits is 1296000, while the sum is 49.

Multiplying 20124545909521 by its sum of digits (49), we get a square (986102749566529 = 31402273²).

The spelling of 20124545909521 in words is "twenty trillion, one hundred twenty-four billion, five hundred forty-five million, nine hundred nine thousand, five hundred twenty-one".