81519251 has 8 divisors (see below), whose sum is σ = 91334064. Its totient is φ = 72105120.

The previous prime is 81519169. The next prime is 81519259. The reversal of 81519251 is 15291518.

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 81519251 - 2¹⁴ = 81502867 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81519259) 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, 99740 + ... + 100553.

It is an arithmetic number, because the mean of its divisors is an integer number (11416758).

Almost surely, 2^81519251 is an apocalyptic number.

81519251 is a deficient number, since it is larger than the sum of its proper divisors (9814813).

81519251 is a wasteful number, since it uses less digits than its factorization.

81519251 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 200341.

The product of its digits is 3600, while the sum is 32.

The square root of 81519251 is about 9028.8011939570. The cubic root of 81519251 is about 433.5974574538.

The spelling of 81519251 in words is "eighty-one million, five hundred nineteen thousand, two hundred fifty-one".