21500423 has 8 divisors (see below), whose sum is σ = 25640448. Its totient is φ = 17627544.

The previous prime is 21500321. The next prime is 21500429. The reversal of 21500423 is 32400512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21500423 - 2¹² = 21496327 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 (21500429) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 66611 + ... + 66932.

It is an arithmetic number, because the mean of its divisors is an integer number (3205056).

Almost surely, 2^21500423 is an apocalyptic number.

21500423 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

21500423 is a deficient number, since it is larger than the sum of its proper divisors (4140025).

21500423 is a wasteful number, since it uses less digits than its factorization.

21500423 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 133573.

The product of its (nonzero) digits is 240, while the sum is 17.

The square root of 21500423 is about 4636.8548607866. The cubic root of 21500423 is about 278.0667119024.

Adding to 21500423 its reverse (32400512), we get a palindrome (53900935).

The spelling of 21500423 in words is "twenty-one million, five hundred thousand, four hundred twenty-three".