1656121261 has 2 divisors, whose sum is σ = 1656121262. Its totient is φ = 1656121260.

The previous prime is 1656121223. The next prime is 1656121273. The reversal of 1656121261 is 1621216561.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1131986025 + 524135236 = 33645^2 + 22894^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1656121261 is a prime.

It is a super-2 number, since 2×1656121261² = 5485475262272460242, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1656221261) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 828060630 + 828060631.

It is an arithmetic number, because the mean of its divisors is an integer number (828060631).

Almost surely, 2^1656121261 is an apocalyptic number.

It is an amenable number.

1656121261 is a deficient number, since it is larger than the sum of its proper divisors (1).

1656121261 is an equidigital number, since it uses as much as digits as its factorization.

1656121261 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4320, while the sum is 31.

The square root of 1656121261 is about 40695.4697847316. The cubic root of 1656121261 is about 1183.1252167404.

The spelling of 1656121261 in words is "one billion, six hundred fifty-six million, one hundred twenty-one thousand, two hundred sixty-one".