1264507661 has 2 divisors, whose sum is σ = 1264507662. Its totient is φ = 1264507660.

The previous prime is 1264507649. The next prime is 1264507667. The reversal of 1264507661 is 1667054621.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1201939561 + 62568100 = 34669^2 + 7910^2 .

It is a cyclic number.

It is not a de Polignac number, because 1264507661 - 2²² = 1260313357 is a prime.

It is a super-3 number, since 3×1264507661³ (a number of 28 digits) contains 333 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1264507667) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 632253830 + 632253831.

It is an arithmetic number, because the mean of its divisors is an integer number (632253831).

Almost surely, 2^1264507661 is an apocalyptic number.

It is an amenable number.

1264507661 is a deficient number, since it is larger than the sum of its proper divisors (1).

1264507661 is an equidigital number, since it uses as much as digits as its factorization.

1264507661 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 60480, while the sum is 38.

The square root of 1264507661 is about 35559.9164931528. The cubic root of 1264507661 is about 1081.3687666392.

The spelling of 1264507661 in words is "one billion, two hundred sixty-four million, five hundred seven thousand, six hundred sixty-one".