81633616 has 20 divisors (see below), whose sum is σ = 160759924. Its totient is φ = 40147200.

The previous prime is 81633611. The next prime is 81633619. The reversal of 81633616 is 61633618.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 705600 + 80928016 = 840^2 + 8996^2 .

It is a super-2 number, since 2×81633616² = 13328094522470912, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81633611) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 40845 + ... + 42796.

Almost surely, 2^81633616 is an apocalyptic number.

It is an amenable number.

81633616 is a deficient number, since it is larger than the sum of its proper divisors (79126308).

81633616 is a wasteful number, since it uses less digits than its factorization.

81633616 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 83710 (or 83704 counting only the distinct ones).

The product of its digits is 15552, while the sum is 34.

The square root of 81633616 is about 9035.1323177915. The cubic root of 81633616 is about 433.8001302424.

It can be divided in two parts, 81 and 633616, that multiplied together give a square (51322896 = 7164²).

The spelling of 81633616 in words is "eighty-one million, six hundred thirty-three thousand, six hundred sixteen".