731647721 has 4 divisors (see below), whose sum is σ = 836168832. Its totient is φ = 627126612.

The previous prime is 731647673. The next prime is 731647723. The reversal of 731647721 is 127746137.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 731647721 - 2¹⁴ = 731631337 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (731647723) 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, 52260545 + ... + 52260558.

It is an arithmetic number, because the mean of its divisors is an integer number (209042208).

Almost surely, 2^731647721 is an apocalyptic number.

It is an amenable number.

731647721 is a deficient number, since it is larger than the sum of its proper divisors (104521111).

731647721 is a wasteful number, since it uses less digits than its factorization.

731647721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 104521110.

The product of its digits is 49392, while the sum is 38.

The square root of 731647721 is about 27048.9874302163. The cubic root of 731647721 is about 901.0882806392.

The spelling of 731647721 in words is "seven hundred thirty-one million, six hundred forty-seven thousand, seven hundred twenty-one".