18498992121 has 9 divisors (see below), whose sum is σ = 26721355791. Its totient is φ = 12332389392.

The previous prime is 18498992107. The next prime is 18498992137. The reversal of 18498992121 is 12129989481.

The square root of 18498992121 is 136011.

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., 12924279225 + 5574712896 = 113685^2 + 74664^2 .

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

It is not a de Polignac number, because 18498992121 - 2²³ = 18490603513 is a prime.

It is not an unprimeable number, because it can be changed into a prime (18498992921) 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, 385365 + ... + 430701.

Almost surely, 2^18498992121 is an apocalyptic number.

18498992121 is the 136011-st square number.

18498992121 is the 68006-th centered octagonal number.

It is an amenable number.

18498992121 is a deficient number, since it is larger than the sum of its proper divisors (8222363670).

18498992121 is an frugal number, since it uses more digits than its factorization.

18498992121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 90680 (or 45340 counting only the distinct ones).

The product of its digits is 746496, while the sum is 54.

The spelling of 18498992121 in words is "eighteen billion, four hundred ninety-eight million, nine hundred ninety-two thousand, one hundred twenty-one".