21872423 has 4 divisors (see below), whose sum is σ = 22381128. Its totient is φ = 21363720.

The previous prime is 21872419. The next prime is 21872429. The reversal of 21872423 is 32427812.

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 21872423 - 2² = 21872419 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21872429) 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, 254288 + ... + 254373.

It is an arithmetic number, because the mean of its divisors is an integer number (5595282).

Almost surely, 2^21872423 is an apocalyptic number.

21872423 is a deficient number, since it is larger than the sum of its proper divisors (508705).

21872423 is an equidigital number, since it uses as much as digits as its factorization.

21872423 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 508704.

The product of its digits is 5376, while the sum is 29.

The square root of 21872423 is about 4676.7962324651. The cubic root of 21872423 is about 279.6612527599.

The spelling of 21872423 in words is "twenty-one million, eight hundred seventy-two thousand, four hundred twenty-three".