206981136411921 has 9 divisors (see below), whose sum is σ = 298972814937979. Its totient is φ = 137987395500936.

The previous prime is 206981136411899. The next prime is 206981136411949. The reversal of 206981136411921 is 129114631189602.

The square root of 206981136411921 is 14386839.

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

206981136411921 is a `hidden beast` number, since 2 + 0 + 6 + 9 + 8 + 1 + 136 + 411 + 92 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 47434832417025 + 159546303994896 = 6887295^2 + 12631164^2 .

It is a tau number, because it is divible by the number of its divisors (9).

It is not a de Polignac number, because 206981136411921 - 2³⁷ = 206843697458449 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (206981136411961) 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, 40762711 + ... + 45558323.

Almost surely, 2^{206981136411921} is an apocalyptic number.

206981136411921 is the 14386839-th square number.

206981136411921 is the 7193420-th centered octagonal number.

It is an amenable number.

206981136411921 is a deficient number, since it is larger than the sum of its proper divisors (91991678526058).

206981136411921 is an frugal number, since it uses more digits than its factorization.

206981136411921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9591232 (or 4795616 counting only the distinct ones).

The product of its (nonzero) digits is 1119744, while the sum is 54.

The spelling of 206981136411921 in words is "two hundred six trillion, nine hundred eighty-one billion, one hundred thirty-six million, four hundred eleven thousand, nine hundred twenty-one".