21887123 has 4 divisors (see below), whose sum is σ = 21970608. Its totient is φ = 21803640.

The previous prime is 21887119. The next prime is 21887149. The reversal of 21887123 is 32178812.

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 21887123 - 2² = 21887119 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21887123.

It is not an unprimeable number, because it can be changed into a prime (21887423) 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, 41348 + ... + 41873.

It is an arithmetic number, because the mean of its divisors is an integer number (5492652).

Almost surely, 2^21887123 is an apocalyptic number.

21887123 is a deficient number, since it is larger than the sum of its proper divisors (83485).

21887123 is an equidigital number, since it uses as much as digits as its factorization.

21887123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 83484.

The product of its digits is 5376, while the sum is 32.

The square root of 21887123 is about 4678.3675571721. The cubic root of 21887123 is about 279.7238902309.

The spelling of 21887123 in words is "twenty-one million, eight hundred eighty-seven thousand, one hundred twenty-three".