1264515661 has 4 divisors (see below), whose sum is σ = 1269553824. Its totient is φ = 1259477500.

The previous prime is 1264515631. The next prime is 1264515667. The reversal of 1264515661 is 1665154621.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1264515661 - 2¹³ = 1264507469 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1264515661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1264515667) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2518705 + ... + 2519206.

It is an arithmetic number, because the mean of its divisors is an integer number (317388456).

Almost surely, 2^1264515661 is an apocalyptic number.

It is an amenable number.

1264515661 is a deficient number, since it is larger than the sum of its proper divisors (5038163).

1264515661 is an equidigital number, since it uses as much as digits as its factorization.

1264515661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5038162.

The product of its digits is 43200, while the sum is 37.

The square root of 1264515661 is about 35560.0289791783. The cubic root of 1264515661 is about 1081.3710470872.

The spelling of 1264515661 in words is "one billion, two hundred sixty-four million, five hundred fifteen thousand, six hundred sixty-one".