81429631 has 4 divisors (see below), whose sum is σ = 81608272. Its totient is φ = 81250992.

The previous prime is 81429613. The next prime is 81429707. The reversal of 81429631 is 13692418.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 13692418 = 2 ⋅6846209.

It is a cyclic number.

It is not a de Polignac number, because 81429631 - 2⁵ = 81429599 is a prime.

It is a super-2 number, since 2×81429631² = 13261569609592322, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81423631) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 88635 + ... + 89548.

It is an arithmetic number, because the mean of its divisors is an integer number (20402068).

Almost surely, 2^81429631 is an apocalyptic number.

81429631 is a deficient number, since it is larger than the sum of its proper divisors (178641).

81429631 is a wasteful number, since it uses less digits than its factorization.

81429631 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 178640.

The product of its digits is 10368, while the sum is 34.

The square root of 81429631 is about 9023.8368225495. The cubic root of 81429631 is about 433.4385041901.

The spelling of 81429631 in words is "eighty-one million, four hundred twenty-nine thousand, six hundred thirty-one".