81956951 has 4 divisors (see below), whose sum is σ = 81991152. Its totient is φ = 81922752.

The previous prime is 81956923. The next prime is 81956957. The reversal of 81956951 is 15965918.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 15965918 = 2 ⋅7982959.

It is a cyclic number.

It is not a de Polignac number, because 81956951 - 2¹⁰ = 81955927 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 (81956957) 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, 13211 + ... + 18396.

It is an arithmetic number, because the mean of its divisors is an integer number (20497788).

Almost surely, 2^81956951 is an apocalyptic number.

81956951 is a deficient number, since it is larger than the sum of its proper divisors (34201).

81956951 is a wasteful number, since it uses less digits than its factorization.

81956951 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34200.

The product of its digits is 97200, while the sum is 44.

The square root of 81956951 is about 9053.0078427007. The cubic root of 81956951 is about 434.3721086087.

The spelling of 81956951 in words is "eighty-one million, nine hundred fifty-six thousand, nine hundred fifty-one".