661986672 has 20 divisors (see below), whose sum is σ = 1710132360. Its totient is φ = 220662208.

The previous prime is 661986671. The next prime is 661986691. The reversal of 661986672 is 276689166.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661986671) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6895647 + ... + 6895742.

It is an arithmetic number, because the mean of its divisors is an integer number (85506618).

Almost surely, 2^661986672 is an apocalyptic number.

It is an amenable number.

661986672 is an abundant number, since it is smaller than the sum of its proper divisors (1048145688).

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

661986672 is a wasteful number, since it uses less digits than its factorization.

661986672 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13791400 (or 13791394 counting only the distinct ones).

The product of its digits is 1306368, while the sum is 51.

The square root of 661986672 is about 25729.1016555184. The cubic root of 661986672 is about 871.5314866692.

The spelling of 661986672 in words is "six hundred sixty-one million, nine hundred eighty-six thousand, six hundred seventy-two".