21237427 has 2 divisors, whose sum is σ = 21237428. Its totient is φ = 21237426.

The previous prime is 21237413. The next prime is 21237431. The reversal of 21237427 is 72473212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21237427 - 2¹⁹ = 20713139 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21237395 and 21237404.

It is not a weakly prime, because it can be changed into another prime (21237407) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10618713 + 10618714.

It is an arithmetic number, because the mean of its divisors is an integer number (10618714).

Almost surely, 2^21237427 is an apocalyptic number.

21237427 is a deficient number, since it is larger than the sum of its proper divisors (1).

21237427 is an equidigital number, since it uses as much as digits as its factorization.

21237427 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4704, while the sum is 28.

The square root of 21237427 is about 4608.4082935434. The cubic root of 21237427 is about 276.9282745127.

The spelling of 21237427 in words is "twenty-one million, two hundred thirty-seven thousand, four hundred twenty-seven".