661605156 has 36 divisors (see below), whose sum is σ = 1760413200. Its totient is φ = 208927728.

The previous prime is 661605149. The next prime is 661605163. The reversal of 661605156 is 651506166.

It is an interprime number because it is at equal distance from previous prime (661605149) and next prime (661605163).

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 661605156.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 482946 + ... + 484313.

Almost surely, 2^661605156 is an apocalyptic number.

It is an amenable number.

661605156 is an abundant number, since it is smaller than the sum of its proper divisors (1098808044).

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

661605156 is a wasteful number, since it uses less digits than its factorization.

661605156 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 967288 (or 967283 counting only the distinct ones).

The product of its (nonzero) digits is 32400, while the sum is 36.

The square root of 661605156 is about 25721.6864921412. The cubic root of 661605156 is about 871.3640275560.

The spelling of 661605156 in words is "six hundred sixty-one million, six hundred five thousand, one hundred fifty-six".