21023919 has 12 divisors (see below), whose sum is σ = 34706256. Its totient is φ = 12013632.

The previous prime is 21023887. The next prime is 21023923. The reversal of 21023919 is 91932012.

It is not a de Polignac number, because 21023919 - 2⁵ = 21023887 is a prime.

It is a super-2 number, since 2×21023919² = 884010340237122, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21023892 and 21023901.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21023969) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 166794 + ... + 166919.

It is an arithmetic number, because the mean of its divisors is an integer number (2892188).

Almost surely, 2^21023919 is an apocalyptic number.

21023919 is a deficient number, since it is larger than the sum of its proper divisors (13682337).

21023919 is a wasteful number, since it uses less digits than its factorization.

21023919 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 333726 (or 333723 counting only the distinct ones).

The product of its (nonzero) digits is 972, while the sum is 27.

The square root of 21023919 is about 4585.1847291031. The cubic root of 21023919 is about 275.9971250488.

The spelling of 21023919 in words is "twenty-one million, twenty-three thousand, nine hundred nineteen".