72070781 has 4 divisors (see below), whose sum is σ = 75864000. Its totient is φ = 68277564.

The previous prime is 72070741. The next prime is 72070807. The reversal of 72070781 is 18707027.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 72070781 - 2⁶ = 72070717 is a prime.

It is a super-2 number, since 2×72070781² = 10388394947899922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (72070711) 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, 1896581 + ... + 1896618.

It is an arithmetic number, because the mean of its divisors is an integer number (18966000).

Almost surely, 2^72070781 is an apocalyptic number.

It is an amenable number.

72070781 is a deficient number, since it is larger than the sum of its proper divisors (3793219).

72070781 is a wasteful number, since it uses less digits than its factorization.

72070781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3793218.

The product of its (nonzero) digits is 5488, while the sum is 32.

The square root of 72070781 is about 8489.4511601163. The cubic root of 72070781 is about 416.1530444192.

The spelling of 72070781 in words is "seventy-two million, seventy thousand, seven hundred eighty-one".