20618421 has 4 divisors (see below), whose sum is σ = 27491232. Its totient is φ = 13745612.

The previous prime is 20618407. The next prime is 20618453. The reversal of 20618421 is 12481602.

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 20618421 - 2⁷ = 20618293 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 20618391 and 20618400.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20618491) 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, 3436401 + ... + 3436406.

It is an arithmetic number, because the mean of its divisors is an integer number (6872808).

Almost surely, 2^20618421 is an apocalyptic number.

It is an amenable number.

20618421 is a deficient number, since it is larger than the sum of its proper divisors (6872811).

20618421 is an equidigital number, since it uses as much as digits as its factorization.

20618421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6872810.

The product of its (nonzero) digits is 768, while the sum is 24.

The square root of 20618421 is about 4540.7511493144. The cubic root of 20618421 is about 274.2111652946.

The spelling of 20618421 in words is "twenty million, six hundred eighteen thousand, four hundred twenty-one".