72921865 has 8 divisors (see below), whose sum is σ = 87833160. Its totient is φ = 58119552.

The previous prime is 72921833. The next prime is 72921869. The reversal of 72921865 is 56812927.

It can be written as a sum of positive squares in 4 ways, for example, as 2143296 + 70778569 = 1464^2 + 8413^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 72921865 - 2⁵ = 72921833 is a prime.

It is not an unprimeable number, because it can be changed into a prime (72921869) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 25764 + ... + 28453.

It is an arithmetic number, because the mean of its divisors is an integer number (10979145).

Almost surely, 2^72921865 is an apocalyptic number.

It is an amenable number.

72921865 is a deficient number, since it is larger than the sum of its proper divisors (14911295).

72921865 is a wasteful number, since it uses less digits than its factorization.

72921865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 54491.

The product of its digits is 60480, while the sum is 40.

The square root of 72921865 is about 8539.4300161076. The cubic root of 72921865 is about 417.7847555992.

The spelling of 72921865 in words is "seventy-two million, nine hundred twenty-one thousand, eight hundred sixty-five".