1266154561 has 6 divisors (see below), whose sum is σ = 1472873730. Its totient is φ = 1085275296.

The previous prime is 1266154517. The next prime is 1266154597. The reversal of 1266154561 is 1654516621.

It can be written as a sum of positive squares in only one way, i.e., 1264513600 + 1640961 = 35560^2 + 1281^2 .

It is not a de Polignac number, because 1266154561 - 2¹⁷ = 1266023489 is a prime.

It is a super-2 number, since 2×1266154561² = 3206294744682205442, which contains 22 as substring.

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 1266154561.

It is not an unprimeable number, because it can be changed into a prime (1266154061) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 12919896 + ... + 12919993.

It is an arithmetic number, because the mean of its divisors is an integer number (245478955).

Almost surely, 2^1266154561 is an apocalyptic number.

It is an amenable number.

1266154561 is a deficient number, since it is larger than the sum of its proper divisors (206719169).

1266154561 is an equidigital number, since it uses as much as digits as its factorization.

1266154561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25839903 (or 25839896 counting only the distinct ones).

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

The square root of 1266154561 is about 35583.0656492664. The cubic root of 1266154561 is about 1081.8380226937.

The spelling of 1266154561 in words is "one billion, two hundred sixty-six million, one hundred fifty-four thousand, five hundred sixty-one".