72013781 has 12 divisors (see below), whose sum is σ = 88181280. Its totient is φ = 58476600.

The previous prime is 72013769. The next prime is 72013787. The reversal of 72013781 is 18731027.

It is not a de Polignac number, because 72013781 - 2¹⁸ = 71751637 is a prime.

It is a super-2 number, since 2×72013781² = 10371969307831922, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (72013787) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 37745 + ... + 39606.

It is an arithmetic number, because the mean of its divisors is an integer number (7348440).

Almost surely, 2^72013781 is an apocalyptic number.

It is an amenable number.

72013781 is a deficient number, since it is larger than the sum of its proper divisors (16167499).

72013781 is a wasteful number, since it uses less digits than its factorization.

72013781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 77384 (or 77377 counting only the distinct ones).

The product of its (nonzero) digits is 2352, while the sum is 29.

The square root of 72013781 is about 8486.0933885976. The cubic root of 72013781 is about 416.0433051719.

The spelling of 72013781 in words is "seventy-two million, thirteen thousand, seven hundred eighty-one".