18121817408 has 14 divisors (see below), whose sum is σ = 35960481546. Its totient is φ = 9060908672.

The previous prime is 18121817407. The next prime is 18121817423. The reversal of 18121817408 is 80471812181.

It can be written as a sum of positive squares in only one way, i.e., 13491287104 + 4630530304 = 116152^2 + 68048^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18121817407) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 141576635 + ... + 141576762.

Almost surely, 2^18121817408 is an apocalyptic number.

It is an amenable number.

18121817408 is a deficient number, since it is larger than the sum of its proper divisors (17838664138).

18121817408 is an equidigital number, since it uses as much as digits as its factorization.

18121817408 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 283153409 (or 283153399 counting only the distinct ones).

The product of its (nonzero) digits is 28672, while the sum is 41.

The spelling of 18121817408 in words is "eighteen billion, one hundred twenty-one million, eight hundred seventeen thousand, four hundred eight".