2154857561 has 2 divisors, whose sum is σ = 2154857562. Its totient is φ = 2154857560.

The previous prime is 2154857527. The next prime is 2154857569. The reversal of 2154857561 is 1657584512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1735222336 + 419635225 = 41656^2 + 20485^2 .

It is a cyclic number.

It is not a de Polignac number, because 2154857561 - 2²⁶ = 2087748697 is a prime.

It is a super-2 number, since 2×2154857561² = 9286822216397737442, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (2154857569) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1077428780 + 1077428781.

It is an arithmetic number, because the mean of its divisors is an integer number (1077428781).

Almost surely, 2^2154857561 is an apocalyptic number.

It is an amenable number.

2154857561 is a deficient number, since it is larger than the sum of its proper divisors (1).

2154857561 is an equidigital number, since it uses as much as digits as its factorization.

2154857561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 336000, while the sum is 44.

The square root of 2154857561 is about 46420.4433520405. The cubic root of 2154857561 is about 1291.6341609820.

The spelling of 2154857561 in words is "two billion, one hundred fifty-four million, eight hundred fifty-seven thousand, five hundred sixty-one".