1266999921 has 32 divisors (see below), whose sum is σ = 2052743040. Its totient is φ = 765979200.

The previous prime is 1266999913. The next prime is 1266999931. The reversal of 1266999921 is 1299996621.

It is not a de Polignac number, because 1266999921 - 2³ = 1266999913 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1266999911) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 119971 + ... + 130103.

It is an arithmetic number, because the mean of its divisors is an integer number (64148220).

Almost surely, 2^1266999921 is an apocalyptic number.

1266999921 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1266999921 is a deficient number, since it is larger than the sum of its proper divisors (785743119).

1266999921 is a wasteful number, since it uses less digits than its factorization.

1266999921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10574 (or 10568 counting only the distinct ones).

The product of its digits is 944784, while the sum is 54.

The square root of 1266999921 is about 35594.9423514072. The cubic root of 1266999921 is about 1082.0787355735.

The spelling of 1266999921 in words is "one billion, two hundred sixty-six million, nine hundred ninety-nine thousand, nine hundred twenty-one".