72857781 has 24 divisors (see below), whose sum is σ = 111178496. Its totient is φ = 45904320.

The previous prime is 72857753. The next prime is 72857783. The reversal of 72857781 is 18775827.

72857781 is a `hidden beast` number, since 72 + 8 + 577 + 8 + 1 = 666.

It is not a de Polignac number, because 72857781 - 2¹³ = 72849589 is a prime.

It is a super-2 number, since 2×72857781² = 10616512504487922, 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 (72857783) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 8961 + ... + 15033.

Almost surely, 2^72857781 is an apocalyptic number.

It is an amenable number.

72857781 is a deficient number, since it is larger than the sum of its proper divisors (38320715).

72857781 is a wasteful number, since it uses less digits than its factorization.

72857781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6153 (or 6150 counting only the distinct ones).

The product of its digits is 219520, while the sum is 45.

The square root of 72857781 is about 8535.6769503069. The cubic root of 72857781 is about 417.6623361441.

The spelling of 72857781 in words is "seventy-two million, eight hundred fifty-seven thousand, seven hundred eighty-one".