21619231 has 2 divisors, whose sum is σ = 21619232. Its totient is φ = 21619230.

The previous prime is 21619229. The next prime is 21619267. The reversal of 21619231 is 13291612.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21619231 - 2¹ = 21619229 is a prime.

It is a super-2 number, since 2×21619231² = 934782298062722, which contains 22 as substring.

Together with 21619229, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 21619196 and 21619205.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21619531) 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, 10809615 + 10809616.

It is an arithmetic number, because the mean of its divisors is an integer number (10809616).

Almost surely, 2^21619231 is an apocalyptic number.

21619231 is a deficient number, since it is larger than the sum of its proper divisors (1).

21619231 is an equidigital number, since it uses as much as digits as its factorization.

21619231 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 648, while the sum is 25.

The square root of 21619231 is about 4649.6484813371. The cubic root of 21619231 is about 278.5779558660.

The spelling of 21619231 in words is "twenty-one million, six hundred nineteen thousand, two hundred thirty-one".