811921887 has 80 divisors (see below), whose sum is σ = 1481179392. Its totient is φ = 432656640.

The previous prime is 811921823. The next prime is 811921897. The reversal of 811921887 is 788129118.

It is a happy number.

It is not a de Polignac number, because 811921887 - 2⁶ = 811921823 is a prime.

It is a super-3 number, since 3×811921887³ (a number of 28 digits) contains 333 as substring.

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (811921897) by changing a digit.

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 in 79 ways as a sum of consecutive naturals, for example, 1262388 + ... + 1263030.

Almost surely, 2^811921887 is an apocalyptic number.

811921887 is a deficient number, since it is larger than the sum of its proper divisors (669257505).

811921887 is a wasteful number, since it uses less digits than its factorization.

811921887 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 810 (or 801 counting only the distinct ones).

The product of its digits is 64512, while the sum is 45.

The square root of 811921887 is about 28494.2430501321. The cubic root of 811921887 is about 932.9064225168.

The spelling of 811921887 in words is "eight hundred eleven million, nine hundred twenty-one thousand, eight hundred eighty-seven".