81863554 has 4 divisors (see below), whose sum is σ = 122795334. Its totient is φ = 40931776.

The previous prime is 81863543. The next prime is 81863563. The reversal of 81863554 is 45536818.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 81812025 + 51529 = 9045^2 + 227^2 .

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20465887 + ... + 20465890.

Almost surely, 2^81863554 is an apocalyptic number.

81863554 is a deficient number, since it is larger than the sum of its proper divisors (40931780).

81863554 is a wasteful number, since it uses less digits than its factorization.

81863554 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40931779.

The product of its digits is 115200, while the sum is 40.

The square root of 81863554 is about 9047.8480314382. The cubic root of 81863554 is about 434.2070444226.

The spelling of 81863554 in words is "eighty-one million, eight hundred sixty-three thousand, five hundred fifty-four".