20421031 has 4 divisors (see below), whose sum is σ = 20755864. Its totient is φ = 20086200.

The previous prime is 20421013. The next prime is 20421043. The reversal of 20421031 is 13012402.

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 20421031 - 2⁵ = 20420999 is a prime.

It is a super-2 number, since 2×20421031² = 834037014205922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20427031) 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, 167325 + ... + 167446.

It is an arithmetic number, because the mean of its divisors is an integer number (5188966).

Almost surely, 2^20421031 is an apocalyptic number.

20421031 is a deficient number, since it is larger than the sum of its proper divisors (334833).

20421031 is an equidigital number, since it uses as much as digits as its factorization.

20421031 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 334832.

The product of its (nonzero) digits is 48, while the sum is 13.

The square root of 20421031 is about 4518.9634873497. The cubic root of 20421031 is about 273.3333063983. Note that the first 4 decimals are identical.

Adding to 20421031 its reverse (13012402), we get a palindrome (33433433).

The spelling of 20421031 in words is "twenty million, four hundred twenty-one thousand, thirty-one".