20668409 has 4 divisors (see below), whose sum is σ = 21756240. Its totient is φ = 19580580.

The previous prime is 20668397. The next prime is 20668429. The reversal of 20668409 is 90486602.

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 a cyclic number.

It is not a de Polignac number, because 20668409 - 2¹² = 20664313 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20668429) 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, 543887 + ... + 543924.

It is an arithmetic number, because the mean of its divisors is an integer number (5439060).

Almost surely, 2^20668409 is an apocalyptic number.

It is an amenable number.

20668409 is a deficient number, since it is larger than the sum of its proper divisors (1087831).

20668409 is a wasteful number, since it uses less digits than its factorization.

20668409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1087830.

The product of its (nonzero) digits is 20736, while the sum is 35.

The square root of 20668409 is about 4546.2521927407. The cubic root of 20668409 is about 274.4325887355.

The spelling of 20668409 in words is "twenty million, six hundred sixty-eight thousand, four hundred nine".