20423251 has 4 divisors (see below), whose sum is σ = 20584192. Its totient is φ = 20262312.

The previous prime is 20423231. The next prime is 20423257. The reversal of 20423251 is 15232402.

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 20423251 - 2¹⁵ = 20390483 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20423257) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 80280 + ... + 80533.

It is an arithmetic number, because the mean of its divisors is an integer number (5146048).

Almost surely, 2^20423251 is an apocalyptic number.

20423251 is a deficient number, since it is larger than the sum of its proper divisors (160941).

20423251 is a wasteful number, since it uses less digits than its factorization.

20423251 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 160940.

The product of its (nonzero) digits is 480, while the sum is 19.

The square root of 20423251 is about 4519.2091122231. The cubic root of 20423251 is about 273.3432108599.

Adding to 20423251 its reverse (15232402), we get a palindrome (35655653).

The spelling of 20423251 in words is "twenty million, four hundred twenty-three thousand, two hundred fifty-one".