661636968 has 48 divisors (see below), whose sum is σ = 1709231040. Its totient is φ = 213423840.

The previous prime is 661636951. The next prime is 661637017. The reversal of 661636968 is 869636166.

It is a self number, because there is not a number n which added to its sum of digits gives 661636968.

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, 8721 + ... + 37407.

It is an arithmetic number, because the mean of its divisors is an integer number (35608980).

Almost surely, 2^661636968 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 661636968, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (854615520).

661636968 is an abundant number, since it is smaller than the sum of its proper divisors (1047594072).

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

661636968 is a wasteful number, since it uses less digits than its factorization.

661636968 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28758 (or 28723 counting only the distinct ones).

The product of its digits is 1679616, while the sum is 51.

The square root of 661636968 is about 25722.3048733973. The cubic root of 661636968 is about 871.3779932816.

The spelling of 661636968 in words is "six hundred sixty-one million, six hundred thirty-six thousand, nine hundred sixty-eight".