721753506 has 12 divisors (see below), whose sum is σ = 1563799302. Its totient is φ = 240584496.

The previous prime is 721753493. The next prime is 721753507. The reversal of 721753506 is 605357127.

It can be written as a sum of positive squares in only one way, i.e., 721728225 + 25281 = 26865^2 + 159^2 .

It is not an unprimeable number, because it can be changed into a prime (721753507) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 20048691 + ... + 20048726.

Almost surely, 2^721753506 is an apocalyptic number.

721753506 is an abundant number, since it is smaller than the sum of its proper divisors (842045796).

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

721753506 is a wasteful number, since it uses less digits than its factorization.

721753506 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40097425 (or 40097422 counting only the distinct ones).

The product of its (nonzero) digits is 44100, while the sum is 36.

The square root of 721753506 is about 26865.4705151427. The cubic root of 721753506 is about 897.0079677745.

The spelling of 721753506 in words is "seven hundred twenty-one million, seven hundred fifty-three thousand, five hundred six".