20939609 has 2 divisors, whose sum is σ = 20939610. Its totient is φ = 20939608.

The previous prime is 20939603. The next prime is 20939621. The reversal of 20939609 is 90693902.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17598025 + 3341584 = 4195^2 + 1828^2 .

It is a cyclic number.

It is not a de Polignac number, because 20939609 - 2⁴ = 20939593 is a prime.

It is not a weakly prime, because it can be changed into another prime (20939603) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10469804 + 10469805.

It is an arithmetic number, because the mean of its divisors is an integer number (10469805).

Almost surely, 2^20939609 is an apocalyptic number.

It is an amenable number.

20939609 is a deficient number, since it is larger than the sum of its proper divisors (1).

20939609 is an equidigital number, since it uses as much as digits as its factorization.

20939609 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 26244, while the sum is 38.

The square root of 20939609 is about 4575.9817525860. The cubic root of 20939609 is about 275.6276967495.

The spelling of 20939609 in words is "twenty million, nine hundred thirty-nine thousand, six hundred nine".