81563788 has 6 divisors (see below), whose sum is σ = 142736636. Its totient is φ = 40781892.

The previous prime is 81563761. The next prime is 81563809. The reversal of 81563788 is 88736518.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10195470 + ... + 10195477.

Almost surely, 2^81563788 is an apocalyptic number.

It is an amenable number.

81563788 is a deficient number, since it is larger than the sum of its proper divisors (61172848).

81563788 is a wasteful number, since it uses less digits than its factorization.

81563788 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20390951 (or 20390949 counting only the distinct ones).

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

The square root of 81563788 is about 9031.2672421981. The cubic root of 81563788 is about 433.6764065527.

It can be divided in two parts, 8 and 1563788, that added together give a triangular number (1563796 = T₁₇₆₈).

The spelling of 81563788 in words is "eighty-one million, five hundred sixty-three thousand, seven hundred eighty-eight".