691000660 has 24 divisors (see below), whose sum is σ = 1658401920. Its totient is φ = 236914464.

The previous prime is 691000643. The next prime is 691000693. The reversal of 691000660 is 66000196.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (28).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2467720 + ... + 2467999.

It is an arithmetic number, because the mean of its divisors is an integer number (69100080).

Almost surely, 2^691000660 is an apocalyptic number.

It is an amenable number.

691000660 is an abundant number, since it is smaller than the sum of its proper divisors (967401260).

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

691000660 is a wasteful number, since it uses less digits than its factorization.

691000660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4935735 (or 4935733 counting only the distinct ones).

The product of its (nonzero) digits is 1944, while the sum is 28.

The square root of 691000660 is about 26286.8914099785. The cubic root of 691000660 is about 884.0825544136.

The spelling of 691000660 in words is "six hundred ninety-one million, six hundred sixty", and thus it is an aban number.