81916733 has 4 divisors (see below), whose sum is σ = 86228160. Its totient is φ = 77605308.

The previous prime is 81916699. The next prime is 81916781. The reversal of 81916733 is 33761918.

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, and also an emirpimes, since its reverse is a distinct semiprime: 33761918 = 2 ⋅16880959.

It is a cyclic number.

It is not a de Polignac number, because 81916733 - 2⁶ = 81916669 is a prime.

It is a super-2 number, since 2×81916733² = 13420702290786578, 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 (81916033) 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, 2155685 + ... + 2155722.

It is an arithmetic number, because the mean of its divisors is an integer number (21557040).

Almost surely, 2^81916733 is an apocalyptic number.

It is an amenable number.

81916733 is a deficient number, since it is larger than the sum of its proper divisors (4311427).

81916733 is a wasteful number, since it uses less digits than its factorization.

81916733 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4311426.

The product of its digits is 27216, while the sum is 38.

The square root of 81916733 is about 9050.7863194310. The cubic root of 81916733 is about 434.3010451394.

The spelling of 81916733 in words is "eighty-one million, nine hundred sixteen thousand, seven hundred thirty-three".