81351951 has 4 divisors (see below), whose sum is σ = 108469272. Its totient is φ = 54234632.

The previous prime is 81351947. The next prime is 81351983. The reversal of 81351951 is 15915318.

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 81351951 - 2² = 81351947 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81351451) 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, 13558656 + ... + 13558661.

It is an arithmetic number, because the mean of its divisors is an integer number (27117318).

Almost surely, 2^81351951 is an apocalyptic number.

81351951 is a deficient number, since it is larger than the sum of its proper divisors (27117321).

81351951 is a wasteful number, since it uses less digits than its factorization.

81351951 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27117320.

The product of its digits is 5400, while the sum is 33.

The square root of 81351951 is about 9019.5316397250. The cubic root of 81351951 is about 433.3006337587.

The spelling of 81351951 in words is "eighty-one million, three hundred fifty-one thousand, nine hundred fifty-one".