21213427 has 2 divisors, whose sum is σ = 21213428. Its totient is φ = 21213426.

The previous prime is 21213419. The next prime is 21213431. The reversal of 21213427 is 72431212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21213427 - 2³ = 21213419 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21213398 and 21213407.

It is not a weakly prime, because it can be changed into another prime (21213407) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10606713 + 10606714.

It is an arithmetic number, because the mean of its divisors is an integer number (10606714).

Almost surely, 2^21213427 is an apocalyptic number.

21213427 is a deficient number, since it is larger than the sum of its proper divisors (1).

21213427 is an equidigital number, since it uses as much as digits as its factorization.

21213427 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 672, while the sum is 22.

The square root of 21213427 is about 4605.8036215193. The cubic root of 21213427 is about 276.8239181207.

Adding to 21213427 its reverse (72431212), we get a palindrome (93644639).

The spelling of 21213427 in words is "twenty-one million, two hundred thirteen thousand, four hundred twenty-seven".