721621405 has 8 divisors (see below), whose sum is σ = 867670272. Its totient is φ = 576147408.

The previous prime is 721621393. The next prime is 721621421. The reversal of 721621405 is 504126127.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-721621405 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 140949 + ... + 145978.

It is an arithmetic number, because the mean of its divisors is an integer number (108458784).

Almost surely, 2^721621405 is an apocalyptic number.

It is an amenable number.

721621405 is a deficient number, since it is larger than the sum of its proper divisors (146048867).

721621405 is a wasteful number, since it uses less digits than its factorization.

721621405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 287435.

The product of its (nonzero) digits is 3360, while the sum is 28.

The square root of 721621405 is about 26863.0118378413. The cubic root of 721621405 is about 896.9532386190.

The spelling of 721621405 in words is "seven hundred twenty-one million, six hundred twenty-one thousand, four hundred five".