81653788 has 24 divisors (see below), whose sum is σ = 152334000. Its totient is φ = 38162688.

The previous prime is 81653779. The next prime is 81653797. The reversal of 81653788 is 88735618.

It is an interprime number because it is at equal distance from previous prime (81653779) and next prime (81653797).

It is a hoax number, since the sum of its digits (46) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

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, 6103 + ... + 14161.

It is an arithmetic number, because the mean of its divisors is an integer number (6347250).

Almost surely, 2^81653788 is an apocalyptic number.

It is an amenable number.

81653788 is a deficient number, since it is larger than the sum of its proper divisors (70680212).

81653788 is a wasteful number, since it uses less digits than its factorization.

81653788 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8229 (or 8227 counting only the distinct ones).

The product of its digits is 322560, while the sum is 46.

The square root of 81653788 is about 9036.2485578917. The cubic root of 81653788 is about 433.8358585611.

It can be divided in two parts, 8 and 1653788, that added together give a square (1653796 = 1286²).

The spelling of 81653788 in words is "eighty-one million, six hundred fifty-three thousand, seven hundred eighty-eight".