1265351661 has 12 divisors (see below), whose sum is σ = 2088834592. Its totient is φ = 723058056.

The previous prime is 1265351629. The next prime is 1265351671. The reversal of 1265351661 is 1661535621.

It is not a de Polignac number, because 1265351661 - 2⁵ = 1265351629 is a prime.

It is a super-2 number, since 2×1265351661² = 3202229651990917842, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1265351671) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 10042411 + ... + 10042536.

Almost surely, 2^1265351661 is an apocalyptic number.

It is an amenable number.

1265351661 is a deficient number, since it is larger than the sum of its proper divisors (823482931).

1265351661 is a wasteful number, since it uses less digits than its factorization.

1265351661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20084960 (or 20084957 counting only the distinct ones).

The product of its digits is 32400, while the sum is 36.

The square root of 1265351661 is about 35571.7818080568. The cubic root of 1265351661 is about 1081.6093009031.

The spelling of 1265351661 in words is "one billion, two hundred sixty-five million, three hundred fifty-one thousand, six hundred sixty-one".