1561451399 has 2 divisors, whose sum is σ = 1561451400. Its totient is φ = 1561451398.

The previous prime is 1561451387. The next prime is 1561451401. The reversal of 1561451399 is 9931541651.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1561451399 - 2²⁸ = 1293015943 is a prime.

Together with 1561451401, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1561451299) 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 as a sum of consecutive naturals, namely, 780725699 + 780725700.

It is an arithmetic number, because the mean of its divisors is an integer number (780725700).

Almost surely, 2^1561451399 is an apocalyptic number.

1561451399 is a deficient number, since it is larger than the sum of its proper divisors (1).

1561451399 is an equidigital number, since it uses as much as digits as its factorization.

1561451399 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 145800, while the sum is 44.

The square root of 1561451399 is about 39515.2046559296. The cubic root of 1561451399 is about 1160.1375676622.

The spelling of 1561451399 in words is "one billion, five hundred sixty-one million, four hundred fifty-one thousand, three hundred ninety-nine".