81145773 has 32 divisors (see below), whose sum is σ = 126403200. Its totient is φ = 51383808.

The previous prime is 81145763. The next prime is 81145781. The reversal of 81145773 is 37754118.

81145773 is a `hidden beast` number, since 81 + 1 + 4 + 577 + 3 = 666.

It is not a de Polignac number, because 81145773 - 2⁸ = 81145517 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81145763) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 42013 + ... + 43901.

It is an arithmetic number, because the mean of its divisors is an integer number (3950100).

Almost surely, 2^81145773 is an apocalyptic number.

It is an amenable number.

81145773 is a deficient number, since it is larger than the sum of its proper divisors (45257427).

81145773 is a wasteful number, since it uses less digits than its factorization.

81145773 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1978 (or 1972 counting only the distinct ones).

The product of its digits is 23520, while the sum is 36.

The square root of 81145773 is about 9008.0948596249. The cubic root of 81145773 is about 432.9342723901.

It can be divided in two parts, 81145 and 773, that added together give a palindrome (81918).

The spelling of 81145773 in words is "eighty-one million, one hundred forty-five thousand, seven hundred seventy-three".