20906423 has 4 divisors (see below), whose sum is σ = 20949840. Its totient is φ = 20863008.

The previous prime is 20906407. The next prime is 20906449. The reversal of 20906423 is 32460902.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20906423 - 2⁴ = 20906407 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20906392 and 20906401.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20906453) 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, 20978 + ... + 21951.

It is an arithmetic number, because the mean of its divisors is an integer number (5237460).

Almost surely, 2^20906423 is an apocalyptic number.

20906423 is a deficient number, since it is larger than the sum of its proper divisors (43417).

20906423 is an equidigital number, since it uses as much as digits as its factorization.

20906423 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43416.

The product of its (nonzero) digits is 2592, while the sum is 26.

The square root of 20906423 is about 4572.3542076265. The cubic root of 20906423 is about 275.4820108521.

The spelling of 20906423 in words is "twenty million, nine hundred six thousand, four hundred twenty-three".