81868658 has 4 divisors (see below), whose sum is σ = 122802990. Its totient is φ = 40934328.

The previous prime is 81868643. The next prime is 81868667. The reversal of 81868658 is 85686818.

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., 81848209 + 20449 = 9047^2 + 143^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20467163 + ... + 20467166.

Almost surely, 2^81868658 is an apocalyptic number.

81868658 is a deficient number, since it is larger than the sum of its proper divisors (40934332).

81868658 is a wasteful number, since it uses less digits than its factorization.

81868658 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40934331.

The product of its digits is 737280, while the sum is 50.

The square root of 81868658 is about 9048.1300830614. The cubic root of 81868658 is about 434.2160681643.

The spelling of 81868658 in words is "eighty-one million, eight hundred sixty-eight thousand, six hundred fifty-eight".