72840072321 has 9 divisors (see below), whose sum is σ = 105214607329. Its totient is φ = 48559508436.

The previous prime is 72840072313. The next prime is 72840072337. The reversal of 72840072321 is 12327004827.

The square root of 72840072321 is 269889.

It is a perfect power (a square), and thus also a powerful number.

It is a tau number, because it is divible by the number of its divisors (9).

It is not a de Polignac number, because 72840072321 - 2³ = 72840072313 is a prime.

It is a super-2 number, since 2×72840072321² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (72840072301) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 764686 + ... + 854648.

Almost surely, 2^72840072321 is an apocalyptic number.

72840072321 is the 269889-th square number.

72840072321 is the 134945-th centered octagonal number.

It is an amenable number.

72840072321 is a deficient number, since it is larger than the sum of its proper divisors (32374535008).

72840072321 is an frugal number, since it uses more digits than its factorization.

72840072321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 179932 (or 89966 counting only the distinct ones).

The product of its (nonzero) digits is 37632, while the sum is 36.

Multiplying 72840072321 by its sum of digits (36), we get a square (2622242603556 = 1619334²).

The spelling of 72840072321 in words is "seventy-two billion, eight hundred forty million, seventy-two thousand, three hundred twenty-one".