20708409 has 4 divisors (see below), whose sum is σ = 27611216. Its totient is φ = 13805604.

The previous prime is 20708399. The next prime is 20708447. The reversal of 20708409 is 90480702.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 20708409 - 2⁵ = 20708377 is a prime.

It is a super-2 number, since 2×20708409² = 857676406622562, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (20708489) 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, 3451399 + ... + 3451404.

It is an arithmetic number, because the mean of its divisors is an integer number (6902804).

Almost surely, 2^20708409 is an apocalyptic number.

It is an amenable number.

20708409 is a deficient number, since it is larger than the sum of its proper divisors (6902807).

20708409 is an equidigital number, since it uses as much as digits as its factorization.

20708409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6902806.

The product of its (nonzero) digits is 4032, while the sum is 30.

The square root of 20708409 is about 4550.6492943315. The cubic root of 20708409 is about 274.6095130070.

The spelling of 20708409 in words is "twenty million, seven hundred eight thousand, four hundred nine".