21304923 has 16 divisors (see below), whose sum is σ = 29880576. Its totient is φ = 13476320.

The previous prime is 21304919. The next prime is 21304931. The reversal of 21304923 is 32940312.

It is a cyclic number.

It is not a de Polignac number, because 21304923 - 2² = 21304919 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21304893 and 21304902.

It is not an unprimeable number, because it can be changed into a prime (21304963) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7861 + ... + 10217.

It is an arithmetic number, because the mean of its divisors is an integer number (1867536).

Almost surely, 2^21304923 is an apocalyptic number.

21304923 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

21304923 is a deficient number, since it is larger than the sum of its proper divisors (8575653).

21304923 is a wasteful number, since it uses less digits than its factorization.

21304923 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2514.

The product of its (nonzero) digits is 1296, while the sum is 24.

The square root of 21304923 is about 4615.7256200949. The cubic root of 21304923 is about 277.2213386412.

The spelling of 21304923 in words is "twenty-one million, three hundred four thousand, nine hundred twenty-three".