12639989 has 2 divisors, whose sum is σ = 12639990. Its totient is φ = 12639988.

The previous prime is 12639961. The next prime is 12640003. The reversal of 12639989 is 98993621.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 9891025 + 2748964 = 3145^2 + 1658^2 .

It is a cyclic number.

It is not a de Polignac number, because 12639989 - 2¹⁶ = 12574453 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (12639919) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6319994 + 6319995.

It is an arithmetic number, because the mean of its divisors is an integer number (6319995).

Almost surely, 2^12639989 is an apocalyptic number.

It is an amenable number.

12639989 is a deficient number, since it is larger than the sum of its proper divisors (1).

12639989 is an equidigital number, since it uses as much as digits as its factorization.

12639989 is an evil number, because the sum of its binary digits is even.

The product of its digits is 209952, while the sum is 47.

The square root of 12639989 is about 3555.2762199300. The cubic root of 12639989 is about 232.9425893293.

The spelling of 12639989 in words is "twelve million, six hundred thirty-nine thousand, nine hundred eighty-nine".