81893661 has 16 divisors (see below), whose sum is σ = 113041920. Its totient is φ = 52680960.

The previous prime is 81893653. The next prime is 81893671. The reversal of 81893661 is 16639818.

It is not a de Polignac number, because 81893661 - 2³ = 81893653 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81893621) by changing a digit.

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, 36961 + ... + 39113.

It is an arithmetic number, because the mean of its divisors is an integer number (7065120).

Almost surely, 2^81893661 is an apocalyptic number.

It is an amenable number.

81893661 is a deficient number, since it is larger than the sum of its proper divisors (31148259).

81893661 is a wasteful number, since it uses less digits than its factorization.

81893661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2596.

The product of its digits is 62208, while the sum is 42.

The square root of 81893661 is about 9049.5116442822. The cubic root of 81893661 is about 434.2602674121.

The spelling of 81893661 in words is "eighty-one million, eight hundred ninety-three thousand, six hundred sixty-one".