12920639 has 4 divisors (see below), whose sum is σ = 12986424. Its totient is φ = 12854856.

The previous prime is 12920581. The next prime is 12920647. The reversal of 12920639 is 93602921.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 12920639 - 2¹⁶ = 12855103 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12920669) 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, 32597 + ... + 32990.

It is an arithmetic number, because the mean of its divisors is an integer number (3246606).

Almost surely, 2^12920639 is an apocalyptic number.

12920639 is a deficient number, since it is larger than the sum of its proper divisors (65785).

12920639 is an equidigital number, since it uses as much as digits as its factorization.

12920639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 65784.

The product of its (nonzero) digits is 5832, while the sum is 32.

The square root of 12920639 is about 3594.5290373010. The cubic root of 12920639 is about 234.6540193213.

The spelling of 12920639 in words is "twelve million, nine hundred twenty thousand, six hundred thirty-nine".