81646756 has 6 divisors (see below), whose sum is σ = 142881830. Its totient is φ = 40823376.

The previous prime is 81646739. The next prime is 81646769. The reversal of 81646756 is 65764618.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 66977856 + 14668900 = 8184^2 + 3830^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10205841 + ... + 10205848.

Almost surely, 2^81646756 is an apocalyptic number.

It is an amenable number.

81646756 is a deficient number, since it is larger than the sum of its proper divisors (61235074).

81646756 is a wasteful number, since it uses less digits than its factorization.

81646756 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20411693 (or 20411691 counting only the distinct ones).

The product of its digits is 241920, while the sum is 43.

The square root of 81646756 is about 9035.8594499915. The cubic root of 81646756 is about 433.8234042651.

The spelling of 81646756 in words is "eighty-one million, six hundred forty-six thousand, seven hundred fifty-six".