20909421 has 24 divisors (see below), whose sum is σ = 33735520. Its totient is φ = 12865392.

The previous prime is 20909419. The next prime is 20909431. The reversal of 20909421 is 12490902.

It is not a de Polignac number, because 20909421 - 2¹ = 20909419 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20909431) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 151 + ... + 6468.

Almost surely, 2^20909421 is an apocalyptic number.

It is an amenable number.

20909421 is a deficient number, since it is larger than the sum of its proper divisors (12826099).

20909421 is an equidigital number, since it uses as much as digits as its factorization.

20909421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6647 (or 6635 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 27.

The square root of 20909421 is about 4572.6820357423. The cubic root of 20909421 is about 275.4951783461.

It can be divided in two parts, 2090 and 9421, that added together give a palindrome (11511).

The spelling of 20909421 in words is "twenty million, nine hundred nine thousand, four hundred twenty-one".