21827381 has 2 divisors, whose sum is σ = 21827382. Its totient is φ = 21827380.

The previous prime is 21827369. The next prime is 21827387. The reversal of 21827381 is 18372812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17926756 + 3900625 = 4234^2 + 1975^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21827381 is a prime.

It is a super-2 number, since 2×21827381² = 952869122638322, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21827387) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10913690 + 10913691.

It is an arithmetic number, because the mean of its divisors is an integer number (10913691).

Almost surely, 2^21827381 is an apocalyptic number.

It is an amenable number.

21827381 is a deficient number, since it is larger than the sum of its proper divisors (1).

21827381 is an equidigital number, since it uses as much as digits as its factorization.

21827381 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5376, while the sum is 32.

The square root of 21827381 is about 4671.9782747783. The cubic root of 21827381 is about 279.4691515200.

The spelling of 21827381 in words is "twenty-one million, eight hundred twenty-seven thousand, three hundred eighty-one".