81510249 has 4 divisors (see below), whose sum is σ = 108680336. Its totient is φ = 54340164.

The previous prime is 81510239. The next prime is 81510263. The reversal of 81510249 is 94201518.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 81510249 - 2⁹ = 81509737 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81510239) 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, 13585039 + ... + 13585044.

It is an arithmetic number, because the mean of its divisors is an integer number (27170084).

Almost surely, 2^81510249 is an apocalyptic number.

It is an amenable number.

81510249 is a deficient number, since it is larger than the sum of its proper divisors (27170087).

81510249 is a wasteful number, since it uses less digits than its factorization.

81510249 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27170086.

The product of its (nonzero) digits is 2880, while the sum is 30.

The square root of 81510249 is about 9028.3026643993. The cubic root of 81510249 is about 433.5814964468.

The spelling of 81510249 in words is "eighty-one million, five hundred ten thousand, two hundred forty-nine".