813947881 has 2 divisors, whose sum is σ = 813947882. Its totient is φ = 813947880.

The previous prime is 813947863. The next prime is 813947887. The reversal of 813947881 is 188749318.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 631265625 + 182682256 = 25125^2 + 13516^2 .

It is a cyclic number.

It is not a de Polignac number, because 813947881 - 2¹¹ = 813945833 is a prime.

It is a super-2 number, since 2×813947881² = 1325022305968780322, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (813947887) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 406973940 + 406973941.

It is an arithmetic number, because the mean of its divisors is an integer number (406973941).

Almost surely, 2^813947881 is an apocalyptic number.

It is an amenable number.

813947881 is a deficient number, since it is larger than the sum of its proper divisors (1).

813947881 is an equidigital number, since it uses as much as digits as its factorization.

813947881 is an evil number, because the sum of its binary digits is even.

The product of its digits is 387072, while the sum is 49.

The square root of 813947881 is about 28529.7718357508. The cubic root of 813947881 is about 933.6817404898.

The spelling of 813947881 in words is "eight hundred thirteen million, nine hundred forty-seven thousand, eight hundred eighty-one".