81902687 has 4 divisors (see below), whose sum is σ = 83245416. Its totient is φ = 80559960.

The previous prime is 81902683. The next prime is 81902693. The reversal of 81902687 is 78620918.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 78620918 = 2 ⋅39310459.

It is a cyclic number.

It is not a de Polignac number, because 81902687 - 2² = 81902683 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81902683) 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, 671273 + ... + 671394.

It is an arithmetic number, because the mean of its divisors is an integer number (20811354).

Almost surely, 2^81902687 is an apocalyptic number.

81902687 is a deficient number, since it is larger than the sum of its proper divisors (1342729).

81902687 is a wasteful number, since it uses less digits than its factorization.

81902687 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1342728.

The product of its (nonzero) digits is 48384, while the sum is 41.

The square root of 81902687 is about 9050.0103314858. The cubic root of 81902687 is about 434.2762209838.

The spelling of 81902687 in words is "eighty-one million, nine hundred two thousand, six hundred eighty-seven".