81698818 has 4 divisors (see below), whose sum is σ = 122548230. Its totient is φ = 40849408.

The previous prime is 81698807. The next prime is 81698863. The reversal of 81698818 is 81889618.

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., 81054009 + 644809 = 9003^2 + 803^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20424703 + ... + 20424706.

Almost surely, 2^81698818 is an apocalyptic number.

81698818 is a deficient number, since it is larger than the sum of its proper divisors (40849412).

81698818 is a wasteful number, since it uses less digits than its factorization.

81698818 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40849411.

The product of its digits is 221184, while the sum is 49.

The square root of 81698818 is about 9038.7398457971. The cubic root of 81698818 is about 433.9155937420.

The spelling of 81698818 in words is "eighty-one million, six hundred ninety-eight thousand, eight hundred eighteen".