72921 has 8 divisors (see below), whose sum is σ = 98560. Its totient is φ = 47952.

The previous prime is 72911. The next prime is 72923. The reversal of 72921 is 12927.

It is a happy number.

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

It is not a de Polignac number, because 72921 - 2⁵ = 72889 is a prime.

It is an alternating number because its digits alternate between odd and even.

It is a Duffinian number.

72921 is a lucky number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 72921.

It is not an unprimeable number, because it can be changed into a prime (72923) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 216 + ... + 438.

It is an arithmetic number, because the mean of its divisors is an integer number (12320).

2⁷²⁹²¹ is an apocalyptic number.

It is an amenable number.

72921 is a deficient number, since it is larger than the sum of its proper divisors (25639).

72921 is a wasteful number, since it uses less digits than its factorization.

72921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 335.

The product of its digits is 252, while the sum is 21.

The square root of 72921 is about 270.0388860887. The cubic root of 72921 is about 41.7783103670.

Subtracting from 72921 its sum of digits (21), we obtain a square (72900 = 270²).

The spelling of 72921 in words is "seventy-two thousand, nine hundred twenty-one".