20487989165956 has 27 divisors (see below), whose sum is σ = 38824356327813. Its totient is φ = 9455940683280.

The previous prime is 20487989165953. The next prime is 20487989165971. The reversal of 20487989165956 is 65956198978402.

It is a happy number.

The square root of 20487989165956 is 4526366.

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., 3030767628100 + 17457221537856 = 1740910^2 + 4178184^2 .

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20487989165953) 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, 117598471 + ... + 117772561.

Almost surely, 2^{20487989165956} is an apocalyptic number.

20487989165956 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

20487989165956 is the 4526366-th square number.

It is an amenable number.

20487989165956 is a deficient number, since it is larger than the sum of its proper divisors (18336367161857).

20487989165956 is an frugal number, since it uses more digits than its factorization.

20487989165956 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 348212 (or 174106 counting only the distinct ones).

The product of its (nonzero) digits is 2351462400, while the sum is 79.

The spelling of 20487989165956 in words is "twenty trillion, four hundred eighty-seven billion, nine hundred eighty-nine million, one hundred sixty-five thousand, nine hundred fifty-six".