661615550115 has 32 divisors (see below), whose sum is σ = 1147008495360. Its totient is φ = 323720136576.

The previous prime is 661615550051. The next prime is 661615550161. The reversal of 661615550115 is 511055516166.

It is not a de Polignac number, because 661615550115 - 2⁶ = 661615550051 is a prime.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 10375885 + ... + 10439454.

It is an arithmetic number, because the mean of its divisors is an integer number (35844015480).

Almost surely, 2^661615550115 is an apocalyptic number.

661615550115 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

661615550115 is a deficient number, since it is larger than the sum of its proper divisors (485392945245).

661615550115 is a wasteful number, since it uses less digits than its factorization.

661615550115 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20815523.

The product of its (nonzero) digits is 135000, while the sum is 42.

It can be divided in two parts, 66161 and 5550115, that added together give a triangular number (5616276 = T₃₃₅₁).

The spelling of 661615550115 in words is "six hundred sixty-one billion, six hundred fifteen million, five hundred fifty thousand, one hundred fifteen".