21823261 has 2 divisors, whose sum is σ = 21823262. Its totient is φ = 21823260.

The previous prime is 21823247. The next prime is 21823271. The reversal of 21823261 is 16232812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21068100 + 755161 = 4590^2 + 869^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21823261 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21823201) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10911630 + 10911631.

It is an arithmetic number, because the mean of its divisors is an integer number (10911631).

Almost surely, 2^21823261 is an apocalyptic number.

It is an amenable number.

21823261 is a deficient number, since it is larger than the sum of its proper divisors (1).

21823261 is an equidigital number, since it uses as much as digits as its factorization.

21823261 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1152, while the sum is 25.

The square root of 21823261 is about 4671.5373272618. The cubic root of 21823261 is about 279.4515667968.

The spelling of 21823261 in words is "twenty-one million, eight hundred twenty-three thousand, two hundred sixty-one".