721321587 has 24 divisors (see below), whose sum is σ = 1205834240. Its totient is φ = 406963440.

The previous prime is 721321571. The next prime is 721321591. The reversal of 721321587 is 785123127.

721321587 is a `hidden beast` number, since 72 + 1 + 3 + 2 + 1 + 587 = 666.

It is not a de Polignac number, because 721321587 - 2⁴ = 721321571 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (721321507) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 67489 + ... + 77442.

Almost surely, 2^721321587 is an apocalyptic number.

721321587 is a deficient number, since it is larger than the sum of its proper divisors (484512653).

721321587 is a wasteful number, since it uses less digits than its factorization.

721321587 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 145023 (or 145020 counting only the distinct ones).

The product of its digits is 23520, while the sum is 36.

The square root of 721321587 is about 26857.4307594751. The cubic root of 721321587 is about 896.8289998900.

The spelling of 721321587 in words is "seven hundred twenty-one million, three hundred twenty-one thousand, five hundred eighty-seven".