81799951 has 4 divisors (see below), whose sum is σ = 81852400. Its totient is φ = 81747504.

The previous prime is 81799897. The next prime is 81799973. The reversal of 81799951 is 15999718.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81799951 - 2²³ = 73411343 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81799895 and 81799904.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81799451) 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, 23811 + ... + 27028.

It is an arithmetic number, because the mean of its divisors is an integer number (20463100).

Almost surely, 2^81799951 is an apocalyptic number.

81799951 is a deficient number, since it is larger than the sum of its proper divisors (52449).

81799951 is a wasteful number, since it uses less digits than its factorization.

81799951 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52448.

The product of its digits is 204120, while the sum is 49.

The square root of 81799951 is about 9044.3325347977. The cubic root of 81799951 is about 434.0945644703.

The spelling of 81799951 in words is "eighty-one million, seven hundred ninety-nine thousand, nine hundred fifty-one".