21231923 has 2 divisors, whose sum is σ = 21231924. Its totient is φ = 21231922.

The previous prime is 21231893. The next prime is 21231937. The reversal of 21231923 is 32913212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21231923 - 2¹⁴ = 21215539 is a prime.

It is not a weakly prime, because it can be changed into another prime (21231523) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10615961 + 10615962.

It is an arithmetic number, because the mean of its divisors is an integer number (10615962).

Almost surely, 2^21231923 is an apocalyptic number.

21231923 is a deficient number, since it is larger than the sum of its proper divisors (1).

21231923 is an equidigital number, since it uses as much as digits as its factorization.

21231923 is an evil number, because the sum of its binary digits is even.

The product of its digits is 648, while the sum is 23.

The square root of 21231923 is about 4607.8110855373. The cubic root of 21231923 is about 276.9043490639.

It can be divided in two parts, 212 and 31923, that multiplied together give a palindrome (6767676).

The spelling of 21231923 in words is "twenty-one million, two hundred thirty-one thousand, nine hundred twenty-three".