20609639 has 2 divisors, whose sum is σ = 20609640. Its totient is φ = 20609638.

The previous prime is 20609581. The next prime is 20609653. The reversal of 20609639 is 93690602.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20609639 is a prime.

It is a Sophie Germain prime.

It is a junction number, because it is equal to n+sod(n) for n = 20609599 and 20609608.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20609539) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10304819 + 10304820.

It is an arithmetic number, because the mean of its divisors is an integer number (10304820).

Almost surely, 2^20609639 is an apocalyptic number.

20609639 is a deficient number, since it is larger than the sum of its proper divisors (1).

20609639 is an equidigital number, since it uses as much as digits as its factorization.

20609639 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 17496, while the sum is 35.

The square root of 20609639 is about 4539.7840256999. The cubic root of 20609639 is about 274.1722281966.

The spelling of 20609639 in words is "twenty million, six hundred nine thousand, six hundred thirty-nine".