1213954561 has 4 divisors (see below), whose sum is σ = 1215598000. Its totient is φ = 1212311124.

The previous prime is 1213954549. The next prime is 1213954579. The reversal of 1213954561 is 1654593121.

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 not a de Polignac number, because 1213954561 - 2⁷ = 1213954433 is a prime.

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 1213954561.

It is not an unprimeable number, because it can be changed into a prime (1213954541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 820611 + ... + 822088.

It is an arithmetic number, because the mean of its divisors is an integer number (303899500).

Almost surely, 2^1213954561 is an apocalyptic number.

It is an amenable number.

1213954561 is a deficient number, since it is larger than the sum of its proper divisors (1643439).

1213954561 is an equidigital number, since it uses as much as digits as its factorization.

1213954561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1643438.

The product of its digits is 32400, while the sum is 37.

The square root of 1213954561 is about 34841.8507114648. The cubic root of 1213954561 is about 1066.7618529097.

The spelling of 1213954561 in words is "one billion, two hundred thirteen million, nine hundred fifty-four thousand, five hundred sixty-one".