721255905 has 12 divisors (see below), whose sum is σ = 1250176980. Its totient is φ = 384669792.

The previous prime is 721255891. The next prime is 721255921. The reversal of 721255905 is 509552127.

It can be written as a sum of positive squares in 2 ways, for example, as 305585361 + 415670544 = 17481^2 + 20388^2 .

It is not a de Polignac number, because 721255905 - 2¹¹ = 721253857 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 721255905.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 8013910 + ... + 8013999.

It is an arithmetic number, because the mean of its divisors is an integer number (104181415).

Almost surely, 2^721255905 is an apocalyptic number.

It is an amenable number.

721255905 is a deficient number, since it is larger than the sum of its proper divisors (528921075).

721255905 is a wasteful number, since it uses less digits than its factorization.

721255905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16027920 (or 16027917 counting only the distinct ones).

The product of its (nonzero) digits is 31500, while the sum is 36.

The square root of 721255905 is about 26856.2079415542. The cubic root of 721255905 is about 896.8017779539.

The spelling of 721255905 in words is "seven hundred twenty-one million, two hundred fifty-five thousand, nine hundred five".