999997621862121 has 9 divisors (see below), whose sum is σ = 1444441146388279. Its totient is φ = 666665017995936.

The previous prime is 999997621862039. The next prime is 999997621862149. The reversal of 999997621862121 is 121268126799999.

The square root of 999997621862121 is 31622739.

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

999997621862121 is a `hidden beast` number, since 99 + 99 + 97 + 62 + 186 + 2 + 121 = 666.

It can be written as a sum of positive squares in only one way, i.e., 229487504834025 + 770510117028096 = 15148845^2 + 27758064^2 .

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

It is not a de Polignac number, because 999997621862121 - 2²³ = 999997613473513 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (999997621862621) 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, 89597761 + ... + 100138673.

Almost surely, 2^{999997621862121} is an apocalyptic number.

999997621862121 is the 31622739-th square number.

999997621862121 is the 15811370-th centered octagonal number.

It is an amenable number.

999997621862121 is a deficient number, since it is larger than the sum of its proper divisors (444443524526158).

999997621862121 is an frugal number, since it uses more digits than its factorization.

999997621862121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21081832 (or 10540916 counting only the distinct ones).

The product of its digits is 952342272, while the sum is 81.

The spelling of 999997621862121 in words is "nine hundred ninety-nine trillion, nine hundred ninety-seven billion, six hundred twenty-one million, eight hundred sixty-two thousand, one hundred twenty-one".