721764733 has 4 divisors (see below), whose sum is σ = 764221500. Its totient is φ = 679307968.

The previous prime is 721764727. The next prime is 721764737. The reversal of 721764733 is 337467127.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 427745124 + 294019609 = 20682^2 + 17147^2 .

It is a cyclic number.

It is not a de Polignac number, because 721764733 - 2⁹ = 721764221 is a prime.

It is a super-2 number, since 2×721764733² = 1041888659605122578, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721764737) 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, 21228358 + ... + 21228391.

It is an arithmetic number, because the mean of its divisors is an integer number (191055375).

Almost surely, 2^721764733 is an apocalyptic number.

It is an amenable number.

721764733 is a deficient number, since it is larger than the sum of its proper divisors (42456767).

721764733 is a wasteful number, since it uses less digits than its factorization.

721764733 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42456766.

The product of its digits is 148176, while the sum is 40.

The square root of 721764733 is about 26865.6794628388. The cubic root of 721764733 is about 897.0126187881.

The spelling of 721764733 in words is "seven hundred twenty-one million, seven hundred sixty-four thousand, seven hundred thirty-three".