721493406 has 20 divisors (see below), whose sum is σ = 1616680032. Its totient is φ = 240497748.

The previous prime is 721493389. The next prime is 721493419. The reversal of 721493406 is 604394127.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 2226670 + ... + 2226993.

Almost surely, 2^721493406 is an apocalyptic number.

721493406 is an abundant number, since it is smaller than the sum of its proper divisors (895186626).

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

721493406 is a wasteful number, since it uses less digits than its factorization.

721493406 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4453677 (or 4453668 counting only the distinct ones).

The product of its (nonzero) digits is 36288, while the sum is 36.

The square root of 721493406 is about 26860.6292927027. The cubic root of 721493406 is about 896.9002025414.

The spelling of 721493406 in words is "seven hundred twenty-one million, four hundred ninety-three thousand, four hundred six".