2161256551 has 2 divisors, whose sum is σ = 2161256552. Its totient is φ = 2161256550.

The previous prime is 2161256533. The next prime is 2161256579. The reversal of 2161256551 is 1556521612.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 2161256551 - 2⁷ = 2161256423 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2161256501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1080628275 + 1080628276.

It is an arithmetic number, because the mean of its divisors is an integer number (1080628276).

Almost surely, 2^2161256551 is an apocalyptic number.

2161256551 is a deficient number, since it is larger than the sum of its proper divisors (1).

2161256551 is an equidigital number, since it uses as much as digits as its factorization.

2161256551 is an evil number, because the sum of its binary digits is even.

The product of its digits is 18000, while the sum is 34.

The square root of 2161256551 is about 46489.3165254126. The cubic root of 2161256551 is about 1292.9114281194.

The spelling of 2161256551 in words is "two billion, one hundred sixty-one million, two hundred fifty-six thousand, five hundred fifty-one".