1251321761 has 2 divisors, whose sum is σ = 1251321762. Its totient is φ = 1251321760.

The previous prime is 1251321719. The next prime is 1251321767. The reversal of 1251321761 is 1671231521.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1233344161 + 17977600 = 35119^2 + 4240^2 .

It is a cyclic number.

It is not a de Polignac number, because 1251321761 - 2²² = 1247127457 is a prime.

It is a super-2 number, since 2×1251321761² = 3131612299104282242, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1251321767) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 625660880 + 625660881.

It is an arithmetic number, because the mean of its divisors is an integer number (625660881).

Almost surely, 2^1251321761 is an apocalyptic number.

It is an amenable number.

1251321761 is a deficient number, since it is larger than the sum of its proper divisors (1).

1251321761 is an equidigital number, since it uses as much as digits as its factorization.

1251321761 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2520, while the sum is 29.

The square root of 1251321761 is about 35374.0266438527. The cubic root of 1251321761 is about 1077.5968976333.

The spelling of 1251321761 in words is "one billion, two hundred fifty-one million, three hundred twenty-one thousand, seven hundred sixty-one".