81801251 has 8 divisors (see below), whose sum is σ = 98407680. Its totient is φ = 66424968.

The previous prime is 81801221. The next prime is 81801253. The reversal of 81801251 is 15210818.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81801251 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81801251.

It is not an unprimeable number, because it can be changed into a prime (81801253) 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, 307391 + ... + 307656.

It is an arithmetic number, because the mean of its divisors is an integer number (12300960).

Almost surely, 2^81801251 is an apocalyptic number.

81801251 is a deficient number, since it is larger than the sum of its proper divisors (16606429).

81801251 is a wasteful number, since it uses less digits than its factorization.

81801251 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 615073.

The product of its (nonzero) digits is 640, while the sum is 26.

The square root of 81801251 is about 9044.4044027233. The cubic root of 81801251 is about 434.0968640639.

The spelling of 81801251 in words is "eighty-one million, eight hundred one thousand, two hundred fifty-one".