21374281 has 2 divisors, whose sum is σ = 21374282. Its totient is φ = 21374280.

The previous prime is 21374279. The next prime is 21374293. The reversal of 21374281 is 18247312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13756681 + 7617600 = 3709^2 + 2760^2 .

It is a cyclic number.

It is not a de Polignac number, because 21374281 - 2¹ = 21374279 is a prime.

It is a super-2 number, since 2×21374281² = 913719776533922, which contains 22 as substring.

Together with 21374279, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21374231) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10687140 + 10687141.

It is an arithmetic number, because the mean of its divisors is an integer number (10687141).

Almost surely, 2^21374281 is an apocalyptic number.

It is an amenable number.

21374281 is a deficient number, since it is larger than the sum of its proper divisors (1).

21374281 is an equidigital number, since it uses as much as digits as its factorization.

21374281 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2688, while the sum is 28.

The square root of 21374281 is about 4623.2327434383. The cubic root of 21374281 is about 277.5218433689.

The spelling of 21374281 in words is "twenty-one million, three hundred seventy-four thousand, two hundred eighty-one".