72033781 has 4 divisors (see below), whose sum is σ = 72103500. Its totient is φ = 71964064.

The previous prime is 72033779. The next prime is 72033799. The reversal of 72033781 is 18733027.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 18733027 = 113 ⋅165779.

It can be written as a sum of positive squares in 2 ways, for example, as 69872881 + 2160900 = 8359^2 + 1470^2 .

It is a cyclic number.

It is not a de Polignac number, because 72033781 - 2¹ = 72033779 is a prime.

It is a super-2 number, since 2×72033781² = 10377731210311922, 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 (72033721) 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, 33286 + ... + 35383.

It is an arithmetic number, because the mean of its divisors is an integer number (18025875).

Almost surely, 2^72033781 is an apocalyptic number.

It is an amenable number.

72033781 is a deficient number, since it is larger than the sum of its proper divisors (69719).

72033781 is a wasteful number, since it uses less digits than its factorization.

72033781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 69718.

The product of its (nonzero) digits is 7056, while the sum is 31.

The square root of 72033781 is about 8487.2717053244. The cubic root of 72033781 is about 416.0818167633.

The spelling of 72033781 in words is "seventy-two million, thirty-three thousand, seven hundred eighty-one".