690665661 has 24 divisors (see below), whose sum is σ = 1143564864. Its totient is φ = 393482880.

The previous prime is 690665557. The next prime is 690665707. The reversal of 690665661 is 166566096.

It is not a de Polignac number, because 690665661 - 2⁷ = 690665533 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (690665861) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4966 + ... + 37496.

It is an arithmetic number, because the mean of its divisors is an integer number (47648536).

Almost surely, 2^690665661 is an apocalyptic number.

It is an amenable number.

690665661 is a deficient number, since it is larger than the sum of its proper divisors (452899203).

690665661 is a wasteful number, since it uses less digits than its factorization.

690665661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32881 (or 32878 counting only the distinct ones).

The product of its (nonzero) digits is 349920, while the sum is 45.

The square root of 690665661 is about 26280.5186592655. The cubic root of 690665661 is about 883.9396627771.

The spelling of 690665661 in words is "six hundred ninety million, six hundred sixty-five thousand, six hundred sixty-one".