81533764 has 24 divisors (see below), whose sum is σ = 154282968. Its totient is φ = 37478400.

The previous prime is 81533747. The next prime is 81533791. The reversal of 81533764 is 46733518.

It can be written as a sum of positive squares in 4 ways, for example, as 25583364 + 55950400 = 5058^2 + 7480^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10314 + ... + 16414.

It is an arithmetic number, because the mean of its divisors is an integer number (6428457).

Almost surely, 2^81533764 is an apocalyptic number.

It is an amenable number.

81533764 is a deficient number, since it is larger than the sum of its proper divisors (72749204).

81533764 is a wasteful number, since it uses less digits than its factorization.

81533764 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6375 (or 6373 counting only the distinct ones).

The product of its digits is 60480, while the sum is 37.

The square root of 81533764 is about 9029.6048640015. The cubic root of 81533764 is about 433.6231872719.

The spelling of 81533764 in words is "eighty-one million, five hundred thirty-three thousand, seven hundred sixty-four".