721213981905 has 16 divisors (see below), whose sum is σ = 1173500717760. Its totient is φ = 378128008128.

The previous prime is 721213981861. The next prime is 721213981919. The reversal of 721213981905 is 509189312127.

It is a happy number.

721213981905 is digitally balanced in base 2 and base 4, because in such bases it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 721213981905 - 2¹⁰ = 721213980881 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 407464642 + ... + 407466411.

It is an arithmetic number, because the mean of its divisors is an integer number (73343794860).

Almost surely, 2^721213981905 is an apocalyptic number.

It is an amenable number.

721213981905 is a deficient number, since it is larger than the sum of its proper divisors (452286735855).

721213981905 is a wasteful number, since it uses less digits than its factorization.

721213981905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 814931120.

The product of its (nonzero) digits is 272160, while the sum is 48.

The spelling of 721213981905 in words is "seven hundred twenty-one billion, two hundred thirteen million, nine hundred eighty-one thousand, nine hundred five".