21368453 has 2 divisors, whose sum is σ = 21368454. Its totient is φ = 21368452.

The previous prime is 21368429. The next prime is 21368461. The reversal of 21368453 is 35486312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19775809 + 1592644 = 4447^2 + 1262^2 .

It is a cyclic number.

It is not a de Polignac number, because 21368453 - 2¹⁰ = 21367429 is a prime.

It is a super-2 number, since 2×21368453² = 913221567226418, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21368153) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10684226 + 10684227.

It is an arithmetic number, because the mean of its divisors is an integer number (10684227).

Almost surely, 2^21368453 is an apocalyptic number.

It is an amenable number.

21368453 is a deficient number, since it is larger than the sum of its proper divisors (1).

21368453 is an equidigital number, since it uses as much as digits as its factorization.

21368453 is an evil number, because the sum of its binary digits is even.

The product of its digits is 17280, while the sum is 32.

The square root of 21368453 is about 4622.6024055720. The cubic root of 21368453 is about 277.4966176576.

The spelling of 21368453 in words is "twenty-one million, three hundred sixty-eight thousand, four hundred fifty-three".