81902505 has 8 divisors (see below), whose sum is σ = 131044032. Its totient is φ = 43681328.

The previous prime is 81902479. The next prime is 81902507. The reversal of 81902505 is 50520918.

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 81902505 - 2⁷ = 81902377 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81902507) 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, 2730069 + ... + 2730098.

It is an arithmetic number, because the mean of its divisors is an integer number (16380504).

Almost surely, 2^81902505 is an apocalyptic number.

It is an amenable number.

81902505 is a deficient number, since it is larger than the sum of its proper divisors (49141527).

81902505 is a wasteful number, since it uses less digits than its factorization.

81902505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5460175.

The product of its (nonzero) digits is 3600, while the sum is 30.

The square root of 81902505 is about 9050.0002762431. Note that the first 3 decimals coincide. The cubic root of 81902505 is about 434.2758993080.

The spelling of 81902505 in words is "eighty-one million, nine hundred two thousand, five hundred five".