12639561 has 16 divisors (see below), whose sum is σ = 18444288. Its totient is φ = 7635600.

The previous prime is 12639559. The next prime is 12639577. The reversal of 12639561 is 16593621.

It is a happy number.

It is not a de Polignac number, because 12639561 - 2¹ = 12639559 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (12639461) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 19716 + ... + 20346.

It is an arithmetic number, because the mean of its divisors is an integer number (1152768).

Almost surely, 2^12639561 is an apocalyptic number.

12639561 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

12639561 is a deficient number, since it is larger than the sum of its proper divisors (5804727).

12639561 is a wasteful number, since it uses less digits than its factorization.

12639561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1252.

The product of its digits is 9720, while the sum is 33.

The square root of 12639561 is about 3555.2160271916. The cubic root of 12639561 is about 232.9399600930.

The spelling of 12639561 in words is "twelve million, six hundred thirty-nine thousand, five hundred sixty-one".