72218917 has 4 divisors (see below), whose sum is σ = 73980396. Its totient is φ = 70457440.

The previous prime is 72218911. The next prime is 72218929. The reversal of 72218917 is 71981227.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 71981227 = 2143 ⋅33589.

It can be written as a sum of positive squares in 2 ways, for example, as 11519236 + 60699681 = 3394^2 + 7791^2 .

It is a cyclic number.

It is not a de Polignac number, because 72218917 - 2⁷ = 72218789 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 (72218911) 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, 880678 + ... + 880759.

It is an arithmetic number, because the mean of its divisors is an integer number (18495099).

Almost surely, 2^72218917 is an apocalyptic number.

It is an amenable number.

72218917 is a deficient number, since it is larger than the sum of its proper divisors (1761479).

72218917 is a wasteful number, since it uses less digits than its factorization.

72218917 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1761478.

The product of its digits is 14112, while the sum is 37.

The square root of 72218917 is about 8498.1713915407. The cubic root of 72218917 is about 416.4379729187.

The spelling of 72218917 in words is "seventy-two million, two hundred eighteen thousand, nine hundred seventeen".