72831774721921 has 2 divisors, whose sum is σ = 72831774721922. Its totient is φ = 72831774721920.

The previous prime is 72831774721913. The next prime is 72831774721943. The reversal of 72831774721921 is 12912747713827.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 45927729000000 + 26904045721921 = 6777000^2 + 5186911^2 .

It is a cyclic number.

It is not a de Polignac number, because 72831774721921 - 2³ = 72831774721913 is a prime.

It is a super-3 number, since 3×72831774721921³ (a number of 43 digits) contains 333 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 72831774721921.

It is not a weakly prime, because it can be changed into another prime (72831774721621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 36415887360960 + 36415887360961.

It is an arithmetic number, because the mean of its divisors is an integer number (36415887360961).

Almost surely, 2^{72831774721921} is an apocalyptic number.

It is an amenable number.

72831774721921 is a deficient number, since it is larger than the sum of its proper divisors (1).

72831774721921 is an equidigital number, since it uses as much as digits as its factorization.

72831774721921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 16595712, while the sum is 61.

The spelling of 72831774721921 in words is "seventy-two trillion, eight hundred thirty-one billion, seven hundred seventy-four million, seven hundred twenty-one thousand, nine hundred twenty-one".