81351696634 has 24 divisors (see below), whose sum is σ = 132222273372. Its totient is φ = 37522517760.

The previous prime is 81351696581. The next prime is 81351696637. The reversal of 81351696634 is 43669615318.

It can be written as a sum of positive squares in 6 ways, for example, as 2601306009 + 78750390625 = 51003^2 + 280625^2 .

It is a Smith number, since the sum of its digits (52) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (81351696637) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 447424 + ... + 602404.

Almost surely, 2^81351696634 is an apocalyptic number.

81351696634 is a deficient number, since it is larger than the sum of its proper divisors (50870576738).

81351696634 is a wasteful number, since it uses less digits than its factorization.

81351696634 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 156562 (or 156549 counting only the distinct ones).

The product of its digits is 2799360, while the sum is 52.

The spelling of 81351696634 in words is "eighty-one billion, three hundred fifty-one million, six hundred ninety-six thousand, six hundred thirty-four".