661687207 has 8 divisors (see below), whose sum is σ = 696569184. Its totient is φ = 627314688.

The previous prime is 661687133. The next prime is 661687211. The reversal of 661687207 is 702786166.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 661687207 - 2⁷ = 661687079 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661687267) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 124698 + ... + 129895.

It is an arithmetic number, because the mean of its divisors is an integer number (87071148).

Almost surely, 2^661687207 is an apocalyptic number.

661687207 is a deficient number, since it is larger than the sum of its proper divisors (34881977).

661687207 is a wasteful number, since it uses less digits than its factorization.

661687207 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 254729.

The product of its (nonzero) digits is 169344, while the sum is 43.

The square root of 661687207 is about 25723.2814197567. The cubic root of 661687207 is about 871.4000476977.

The spelling of 661687207 in words is "six hundred sixty-one million, six hundred eighty-seven thousand, two hundred seven".