81253764 has 18 divisors (see below), whose sum is σ = 205391550. Its totient is φ = 27084576.

The previous prime is 81253729. The next prime is 81253771. The reversal of 81253764 is 46735218.

It can be written as a sum of positive squares in only one way, i.e., 71064900 + 10188864 = 8430^2 + 3192^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is a Harshad number since it is a multiple of its sum of digits (36), and also a Moran number because the ratio is a prime number: 2257049 = 81253764 / (8 + 1 + 2 + 5 + 3 + 7 + 6 + 4).

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1128489 + ... + 1128560.

Almost surely, 2^81253764 is an apocalyptic number.

It is an amenable number.

81253764 is an abundant number, since it is smaller than the sum of its proper divisors (124137786).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81253764 is a wasteful number, since it uses less digits than its factorization.

81253764 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2257059 (or 2257054 counting only the distinct ones).

The product of its digits is 40320, while the sum is 36.

The square root of 81253764 is about 9014.0869753958. The cubic root of 81253764 is about 433.1262408215.

The spelling of 81253764 in words is "eighty-one million, two hundred fifty-three thousand, seven hundred sixty-four".