21718453 has 2 divisors, whose sum is σ = 21718454. Its totient is φ = 21718452.

The previous prime is 21718451. The next prime is 21718457. The reversal of 21718453 is 35481712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18818244 + 2900209 = 4338^2 + 1703^2 .

It is a cyclic number.

It is not a de Polignac number, because 21718453 - 2¹ = 21718451 is a prime.

Together with 21718451, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21718451) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10859226 + 10859227.

It is an arithmetic number, because the mean of its divisors is an integer number (10859227).

Almost surely, 2^21718453 is an apocalyptic number.

It is an amenable number.

21718453 is a deficient number, since it is larger than the sum of its proper divisors (1).

21718453 is an equidigital number, since it uses as much as digits as its factorization.

21718453 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6720, while the sum is 31.

The square root of 21718453 is about 4660.3061058261. The cubic root of 21718453 is about 279.0034856945.

The spelling of 21718453 in words is "twenty-one million, seven hundred eighteen thousand, four hundred fifty-three".