13661115920 has 40 divisors (see below), whose sum is σ = 32282796120. Its totient is φ = 5374863360.

The previous prime is 13661115907. The next prime is 13661115931. The reversal of 13661115920 is 2951116631.

It can be written as a sum of positive squares in 4 ways, for example, as 175403536 + 13485712384 = 13244^2 + 116128^2 .

It is a tau number, because it is divible by the number of its divisors (40).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1394825 + ... + 1404584.

It is an arithmetic number, because the mean of its divisors is an integer number (807069903).

Almost surely, 2^13661115920 is an apocalyptic number.

13661115920 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

13661115920 is an abundant number, since it is smaller than the sum of its proper divisors (18621680200).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

13661115920 is a wasteful number, since it uses less digits than its factorization.

13661115920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2799483 (or 2799477 counting only the distinct ones).

The product of its (nonzero) digits is 9720, while the sum is 35.

The spelling of 13661115920 in words is "thirteen billion, six hundred sixty-one million, one hundred fifteen thousand, nine hundred twenty".