721687402 has 4 divisors (see below), whose sum is σ = 1082531106. Its totient is φ = 360843700.

The previous prime is 721687297. The next prime is 721687403. The reversal of 721687402 is 204786127.

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

It can be written as a sum of positive squares in only one way, i.e., 714974121 + 6713281 = 26739^2 + 2591^2 .

It is not an unprimeable number, because it can be changed into a prime (721687403) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 180421849 + ... + 180421852.

Almost surely, 2^721687402 is an apocalyptic number.

721687402 is a deficient number, since it is larger than the sum of its proper divisors (360843704).

721687402 is a wasteful number, since it uses less digits than its factorization.

721687402 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 360843703.

The product of its (nonzero) digits is 37632, while the sum is 37.

The square root of 721687402 is about 26864.2402088725. The cubic root of 721687402 is about 896.9805818666.

The spelling of 721687402 in words is "seven hundred twenty-one million, six hundred eighty-seven thousand, four hundred two".