851981839 has 2 divisors, whose sum is σ = 851981840. Its totient is φ = 851981838.

The previous prime is 851981827. The next prime is 851981861. The reversal of 851981839 is 938189158.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-851981839 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (851982839) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 425990919 + 425990920.

It is an arithmetic number, because the mean of its divisors is an integer number (425990920).

Almost surely, 2^851981839 is an apocalyptic number.

851981839 is a deficient number, since it is larger than the sum of its proper divisors (1).

851981839 is an equidigital number, since it uses as much as digits as its factorization.

851981839 is an evil number, because the sum of its binary digits is even.

The product of its digits is 622080, while the sum is 52.

The square root of 851981839 is about 29188.7279441911. The cubic root of 851981839 is about 948.0038748232.

The spelling of 851981839 in words is "eight hundred fifty-one million, nine hundred eighty-one thousand, eight hundred thirty-nine".