721218536 has 32 divisors (see below), whose sum is σ = 1389414600. Its totient is φ = 350760960.

The previous prime is 721218527. The next prime is 721218559. The reversal of 721218536 is 635812127.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 408282436 + 312936100 = 20206^2 + 17690^2 .

It is a junction number, because it is equal to n+sod(n) for n = 721218496 and 721218505.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 112670 + ... + 118898.

Almost surely, 2^721218536 is an apocalyptic number.

It is an amenable number.

721218536 is a deficient number, since it is larger than the sum of its proper divisors (668196064).

721218536 is a wasteful number, since it uses less digits than its factorization.

721218536 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6629 (or 6625 counting only the distinct ones).

The product of its digits is 20160, while the sum is 35.

The square root of 721218536 is about 26855.5122088557. The cubic root of 721218536 is about 896.7862896165.

The spelling of 721218536 in words is "seven hundred twenty-one million, two hundred eighteen thousand, five hundred thirty-six".