21894331 has 2 divisors, whose sum is σ = 21894332. Its totient is φ = 21894330.

The previous prime is 21894329. The next prime is 21894347. The reversal of 21894331 is 13349812.

21894331 = T₃₈₁₉ + T₃₈₂₀ + T₃₈₂₁.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21894331 - 2¹ = 21894329 is a prime.

It is a super-2 number, since 2×21894331² = 958723459875122, which contains 22 as substring.

Together with 21894329, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 21894293 and 21894302.

It is not a weakly prime, because it can be changed into another prime (21894371) 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, 10947165 + 10947166.

It is an arithmetic number, because the mean of its divisors is an integer number (10947166).

Almost surely, 2^21894331 is an apocalyptic number.

21894331 is the 3821-st centered triangular number.

21894331 is a deficient number, since it is larger than the sum of its proper divisors (1).

21894331 is an equidigital number, since it uses as much as digits as its factorization.

21894331 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5184, while the sum is 31.

The square root of 21894331 is about 4679.1378479374. The cubic root of 21894331 is about 279.7545936496.

It can be divided in two parts, 218 and 94331, that added together give a palindrome (94549).

The spelling of 21894331 in words is "twenty-one million, eight hundred ninety-four thousand, three hundred thirty-one".