21813371 has 2 divisors, whose sum is σ = 21813372. Its totient is φ = 21813370.

The previous prime is 21813343. The next prime is 21813377. The reversal of 21813371 is 17331812.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21813371 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21813371.

It is not a weakly prime, because it can be changed into another prime (21813377) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10906685 + 10906686.

It is an arithmetic number, because the mean of its divisors is an integer number (10906686).

Almost surely, 2^21813371 is an apocalyptic number.

21813371 is a deficient number, since it is larger than the sum of its proper divisors (1).

21813371 is an equidigital number, since it uses as much as digits as its factorization.

21813371 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1008, while the sum is 26.

The square root of 21813371 is about 4670.4786692586. The cubic root of 21813371 is about 279.4093458901.

The spelling of 21813371 in words is "twenty-one million, eight hundred thirteen thousand, three hundred seventy-one".