81563955 has 16 divisors (see below), whose sum is σ = 142366464. Its totient is φ = 39546080.

The previous prime is 81563939. The next prime is 81563971. The reversal of 81563955 is 55936518.

It is an interprime number because it is at equal distance from previous prime (81563939) and next prime (81563971).

It is not a de Polignac number, because 81563955 - 2⁴ = 81563939 is a prime.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 246999 + ... + 247328.

It is an arithmetic number, because the mean of its divisors is an integer number (8897904).

Almost surely, 2^81563955 is an apocalyptic number.

81563955 is a deficient number, since it is larger than the sum of its proper divisors (60802509).

81563955 is a wasteful number, since it uses less digits than its factorization.

81563955 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 494346.

The product of its digits is 162000, while the sum is 42.

The square root of 81563955 is about 9031.2764878504. The cubic root of 81563955 is about 433.6767025334.

The spelling of 81563955 in words is "eighty-one million, five hundred sixty-three thousand, nine hundred fifty-five".