81929951 has 8 divisors (see below), whose sum is σ = 84297984. Its totient is φ = 79570080.

The previous prime is 81929927. The next prime is 81929963. The reversal of 81929951 is 15992918.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81929951 - 2¹⁰ = 81928927 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81929251) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 22466 + ... + 25856.

It is an arithmetic number, because the mean of its divisors is an integer number (10537248).

Almost surely, 2^81929951 is an apocalyptic number.

81929951 is a deficient number, since it is larger than the sum of its proper divisors (2368033).

81929951 is a wasteful number, since it uses less digits than its factorization.

81929951 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4081.

The product of its digits is 58320, while the sum is 44.

The square root of 81929951 is about 9051.5165027745. The cubic root of 81929951 is about 434.3244033401.

The spelling of 81929951 in words is "eighty-one million, nine hundred twenty-nine thousand, nine hundred fifty-one".