81501902 has 4 divisors (see below), whose sum is σ = 122252856. Its totient is φ = 40750950.

The previous prime is 81501881. The next prime is 81501913. The reversal of 81501902 is 20910518.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 20910518 = 2 ⋅10455259.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20375474 + ... + 20375477.

It is an arithmetic number, because the mean of its divisors is an integer number (30563214).

Almost surely, 2^81501902 is an apocalyptic number.

81501902 is a deficient number, since it is larger than the sum of its proper divisors (40750954).

81501902 is a wasteful number, since it uses less digits than its factorization.

81501902 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40750953.

The product of its (nonzero) digits is 720, while the sum is 26.

The square root of 81501902 is about 9027.8403840564. The cubic root of 81501902 is about 433.5666957384.

The spelling of 81501902 in words is "eighty-one million, five hundred one thousand, nine hundred two".