21372423 has 16 divisors (see below), whose sum is σ = 29798400. Its totient is φ = 13609440.

The previous prime is 21372413. The next prime is 21372427. The reversal of 21372423 is 32427312.

It is not a de Polignac number, because 21372423 - 2⁸ = 21372167 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21372393 and 21372402.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21372427) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5893 + ... + 8801.

It is an arithmetic number, because the mean of its divisors is an integer number (1862400).

Almost surely, 2^21372423 is an apocalyptic number.

21372423 is a deficient number, since it is larger than the sum of its proper divisors (8425977).

21372423 is a wasteful number, since it uses less digits than its factorization.

21372423 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3022.

The product of its digits is 2016, while the sum is 24.

The square root of 21372423 is about 4623.0317974247. The cubic root of 21372423 is about 277.5138017646.

Adding to 21372423 its reverse (32427312), we get a palindrome (53799735).

It can be divided in two parts, 2137 and 2423, that added together give a triangular number (4560 = T₉₅).

The spelling of 21372423 in words is "twenty-one million, three hundred seventy-two thousand, four hundred twenty-three".