21012323 has 6 divisors (see below), whose sum is σ = 22321356. Its totient is φ = 19776032.

The previous prime is 21012311. The next prime is 21012331. The reversal of 21012323 is 32321012.

It is a happy number.

21012323 is an esthetic number in base 10, because in such base its adjacent digits differ by 1.

It is not a de Polignac number, because 21012323 - 2⁴ = 21012307 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21012298 and 21012307.

It is not an unprimeable number, because it can be changed into a prime (21012373) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 36065 + ... + 36642.

It is an arithmetic number, because the mean of its divisors is an integer number (3720226).

Almost surely, 2^21012323 is an apocalyptic number.

21012323 is a deficient number, since it is larger than the sum of its proper divisors (1309033).

21012323 is an equidigital number, since it uses as much as digits as its factorization.

21012323 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 72741 (or 72724 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 14.

The square root of 21012323 is about 4583.9200472958. The cubic root of 21012323 is about 275.9463725185.

Adding to 21012323 its reverse (32321012), we get a palindrome (53333335).

It can be divided in two parts, 21012 and 323, that multiplied together give a palindrome (6786876).

The spelling of 21012323 in words is "twenty-one million, twelve thousand, three hundred twenty-three".