721690538538 has 8 divisors (see below), whose sum is σ = 1443381077088. Its totient is φ = 240563512844.

The previous prime is 721690538519. The next prime is 721690538573. The reversal of 721690538538 is 835835096127.

It is a happy number.

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

721690538538 is an admirable number.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 60140878206 + ... + 60140878217.

It is an arithmetic number, because the mean of its divisors is an integer number (180422634636).

Almost surely, 2^721690538538 is an apocalyptic number.

721690538538 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

721690538538 is a wasteful number, since it uses less digits than its factorization.

721690538538 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 120281756428.

The product of its (nonzero) digits is 10886400, while the sum is 57.

The spelling of 721690538538 in words is "seven hundred twenty-one billion, six hundred ninety million, five hundred thirty-eight thousand, five hundred thirty-eight".