72078991 has 4 divisors (see below), whose sum is σ = 72359712. Its totient is φ = 71798272.

The previous prime is 72078983. The next prime is 72079019. The reversal of 72078991 is 19987027.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 72078991 - 2³ = 72078983 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (72078911) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 139975 + ... + 140488.

It is an arithmetic number, because the mean of its divisors is an integer number (18089928).

Almost surely, 2^72078991 is an apocalyptic number.

72078991 is a deficient number, since it is larger than the sum of its proper divisors (280721).

72078991 is a wasteful number, since it uses less digits than its factorization.

72078991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 280720.

The product of its (nonzero) digits is 63504, while the sum is 43.

The square root of 72078991 is about 8489.9346876169. The cubic root of 72078991 is about 416.1688459535.

The spelling of 72078991 in words is "seventy-two million, seventy-eight thousand, nine hundred ninety-one".