81990698 has 4 divisors (see below), whose sum is σ = 122986050. Its totient is φ = 40995348.

The previous prime is 81990683. The next prime is 81990709. The reversal of 81990698 is 89609918.

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., 73736569 + 8254129 = 8587^2 + 2873^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20497673 + ... + 20497676.

Almost surely, 2^81990698 is an apocalyptic number.

81990698 is a deficient number, since it is larger than the sum of its proper divisors (40995352).

81990698 is a wasteful number, since it uses less digits than its factorization.

81990698 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40995351.

The product of its (nonzero) digits is 279936, while the sum is 50.

The square root of 81990698 is about 9054.8715065428. The cubic root of 81990698 is about 434.4317201643.

The spelling of 81990698 in words is "eighty-one million, nine hundred ninety thousand, six hundred ninety-eight".