81431613418 has 4 divisors (see below), whose sum is σ = 122147420130. Its totient is φ = 40715806708.

The previous prime is 81431613407. The next prime is 81431613421.

81431613418 is nontrivially palindromic in base 10.

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., 54039046369 + 27392567049 = 232463^2 + 165507^2 .

It is a super-2 number, since 2×81431613418² (a number of 23 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20357903353 + ... + 20357903356.

Almost surely, 2^81431613418 is an apocalyptic number.

81431613418 is a deficient number, since it is larger than the sum of its proper divisors (40715806712).

81431613418 is a wasteful number, since it uses less digits than its factorization.

81431613418 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40715806711.

The product of its digits is 55296, while the sum is 40.

The spelling of 81431613418 in words is "eighty-one billion, four hundred thirty-one million, six hundred thirteen thousand, four hundred eighteen".