1280812561 has 4 divisors (see below), whose sum is σ = 1463785792. Its totient is φ = 1097839332.

The previous prime is 1280812549. The next prime is 1280812583. The reversal of 1280812561 is 1652180821.

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 a de Polignac number, because none of the positive numbers 2^k-1280812561 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1280812501) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 91486605 + ... + 91486618.

It is an arithmetic number, because the mean of its divisors is an integer number (365946448).

Almost surely, 2^1280812561 is an apocalyptic number.

It is an amenable number.

1280812561 is a deficient number, since it is larger than the sum of its proper divisors (182973231).

1280812561 is an equidigital number, since it uses as much as digits as its factorization.

1280812561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 182973230.

The product of its (nonzero) digits is 7680, while the sum is 34.

The square root of 1280812561 is about 35788.4417235509. The cubic root of 1280812561 is about 1085.9967511522.

The spelling of 1280812561 in words is "one billion, two hundred eighty million, eight hundred twelve thousand, five hundred sixty-one".