1266761661 has 16 divisors (see below), whose sum is σ = 1843714560. Its totient is φ = 767254320.

The previous prime is 1266761651. The next prime is 1266761663. The reversal of 1266761661 is 1661676621.

It is a happy number.

It is not a de Polignac number, because 1266761661 - 2¹⁰ = 1266760637 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1266761663) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 45720 + ... + 67998.

It is an arithmetic number, because the mean of its divisors is an integer number (115232160).

Almost surely, 2^1266761661 is an apocalyptic number.

1266761661 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1266761661 is a deficient number, since it is larger than the sum of its proper divisors (576952899).

1266761661 is a wasteful number, since it uses less digits than its factorization.

1266761661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24016.

The product of its digits is 108864, while the sum is 42.

The square root of 1266761661 is about 35591.5953702556. The cubic root of 1266761661 is about 1082.0109028300.

The spelling of 1266761661 in words is "one billion, two hundred sixty-six million, seven hundred sixty-one thousand, six hundred sixty-one".