20423021 has 4 divisors (see below), whose sum is σ = 20432700. Its totient is φ = 20413344.

The previous prime is 20422993. The next prime is 20423023. The reversal of 20423021 is 12032402.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 11356900 + 9066121 = 3370^2 + 3011^2 .

It is a cyclic number.

It is not a de Polignac number, because 20423021 - 2¹⁰ = 20421997 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20422987 and 20423005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20423023) 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, 176 + ... + 6393.

It is an arithmetic number, because the mean of its divisors is an integer number (5108175).

Almost surely, 2^20423021 is an apocalyptic number.

It is an amenable number.

20423021 is a deficient number, since it is larger than the sum of its proper divisors (9679).

20423021 is an equidigital number, since it uses as much as digits as its factorization.

20423021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9678.

The product of its (nonzero) digits is 96, while the sum is 14.

The square root of 20423021 is about 4519.1836652210. The cubic root of 20423021 is about 273.3421847553.

Adding to 20423021 its reverse (12032402), we get a palindrome (32455423).

The spelling of 20423021 in words is "twenty million, four hundred twenty-three thousand, twenty-one".