661679872 has 144 divisors (see below), whose sum is σ = 1600141312. Its totient is φ = 267079680.

The previous prime is 661679869. The next prime is 661679881. The reversal of 661679872 is 278976166.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2388598 + ... + 2388874.

Almost surely, 2^661679872 is an apocalyptic number.

661679872 is a gapful number since it is divisible by the number (62) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 661679872, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (800070656).

661679872 is an abundant number, since it is smaller than the sum of its proper divisors (938461440).

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

661679872 is a wasteful number, since it uses less digits than its factorization.

661679872 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 374 (or 360 counting only the distinct ones).

The product of its digits is 1524096, while the sum is 52.

The square root of 661679872 is about 25723.1388442391. The cubic root of 661679872 is about 871.3968277760.

The spelling of 661679872 in words is "six hundred sixty-one million, six hundred seventy-nine thousand, eight hundred seventy-two".