861505399 has 2 divisors, whose sum is σ = 861505400. Its totient is φ = 861505398.

The previous prime is 861505397. The next prime is 861505417. The reversal of 861505399 is 993505168.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 861505399 - 2¹ = 861505397 is a prime.

It is a super-2 number, since 2×861505399² = 1484383105012298402, which contains 22 as substring.

Together with 861505397, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (861505397) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 430752699 + 430752700.

It is an arithmetic number, because the mean of its divisors is an integer number (430752700).

Almost surely, 2^861505399 is an apocalyptic number.

861505399 is a deficient number, since it is larger than the sum of its proper divisors (1).

861505399 is an equidigital number, since it uses as much as digits as its factorization.

861505399 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 291600, while the sum is 46.

The square root of 861505399 is about 29351.4122147470. The cubic root of 861505399 is about 951.5230965727.

The spelling of 861505399 in words is "eight hundred sixty-one million, five hundred five thousand, three hundred ninety-nine".