999999013263121 has 27 divisors (see below), whose sum is σ = 1031901168183483. Its totient is φ = 969075716113680.

The previous prime is 999999013263079. The next prime is 999999013263137. The reversal of 999999013263121 is 121362310999999.

The square root of 999999013263121 is 31622761.

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., 835689172907521 + 164309840355600 = 28908289^2 + 12818340^2 .

It is not a de Polignac number, because 999999013263121 - 2¹⁹ = 999999012738833 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (999999013263221) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 132467742055 + ... + 132467749603.

Almost surely, 2^{999999013263121} is an apocalyptic number.

999999013263121 is the 31622761-st square number.

999999013263121 is the 15811381-st centered octagonal number.

It is an amenable number.

999999013263121 is a deficient number, since it is larger than the sum of its proper divisors (31902154920362).

999999013263121 is an frugal number, since it uses more digits than its factorization.

999999013263121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15358 (or 7679 counting only the distinct ones).

The product of its (nonzero) digits is 114791256, while the sum is 73.

The spelling of 999999013263121 in words is "nine hundred ninety-nine trillion, nine hundred ninety-nine billion, thirteen million, two hundred sixty-three thousand, one hundred twenty-one".