731666721 has 16 divisors (see below), whose sum is σ = 984299904. Its totient is φ = 483417984.

The previous prime is 731666699. The next prime is 731666753. The reversal of 731666721 is 127666137.

It is not a de Polignac number, because 731666721 - 2⁶ = 731666657 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 731666721.

It is not an unprimeable number, because it can be changed into a prime (731666521) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 349540 + ... + 351626.

It is an arithmetic number, because the mean of its divisors is an integer number (61518744).

Almost surely, 2^731666721 is an apocalyptic number.

It is an amenable number.

731666721 is a deficient number, since it is larger than the sum of its proper divisors (252633183).

731666721 is a wasteful number, since it uses less digits than its factorization.

731666721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3080.

The product of its digits is 63504, while the sum is 39.

The square root of 731666721 is about 27049.3386425620. The cubic root of 731666721 is about 901.0960806267.

The spelling of 731666721 in words is "seven hundred thirty-one million, six hundred sixty-six thousand, seven hundred twenty-one".