861625991 has 2 divisors, whose sum is σ = 861625992. Its totient is φ = 861625990.

The previous prime is 861625937. The next prime is 861626009. The reversal of 861625991 is 199526168.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 861625991 - 2¹⁴ = 861609607 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (861625901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 430812995 + 430812996.

It is an arithmetic number, because the mean of its divisors is an integer number (430812996).

Almost surely, 2^861625991 is an apocalyptic number.

861625991 is a deficient number, since it is larger than the sum of its proper divisors (1).

861625991 is an equidigital number, since it uses as much as digits as its factorization.

861625991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 233280, while the sum is 47.

The square root of 861625991 is about 29353.4664222132. The cubic root of 861625991 is about 951.5674920073.

The spelling of 861625991 in words is "eight hundred sixty-one million, six hundred twenty-five thousand, nine hundred ninety-one".