1261517651 has 2 divisors, whose sum is σ = 1261517652. Its totient is φ = 1261517650.

The previous prime is 1261517611. The next prime is 1261517669. The reversal of 1261517651 is 1567151621.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1261517651 - 2¹⁸ = 1261255507 is a prime.

It is not a weakly prime, because it can be changed into another prime (1261517611) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 630758825 + 630758826.

It is an arithmetic number, because the mean of its divisors is an integer number (630758826).

Almost surely, 2^1261517651 is an apocalyptic number.

1261517651 is a deficient number, since it is larger than the sum of its proper divisors (1).

1261517651 is an equidigital number, since it uses as much as digits as its factorization.

1261517651 is an evil number, because the sum of its binary digits is even.

The product of its digits is 12600, while the sum is 35.

The square root of 1261517651 is about 35517.8497519205. The cubic root of 1261517651 is about 1080.5157718781.

The spelling of 1261517651 in words is "one billion, two hundred sixty-one million, five hundred seventeen thousand, six hundred fifty-one".