21865427 has 2 divisors, whose sum is σ = 21865428. Its totient is φ = 21865426.

The previous prime is 21865421. The next prime is 21865439. The reversal of 21865427 is 72456812.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21865427 - 2⁴ = 21865411 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21865421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10932713 + 10932714.

It is an arithmetic number, because the mean of its divisors is an integer number (10932714).

Almost surely, 2^21865427 is an apocalyptic number.

21865427 is a deficient number, since it is larger than the sum of its proper divisors (1).

21865427 is an equidigital number, since it uses as much as digits as its factorization.

21865427 is an evil number, because the sum of its binary digits is even.

The product of its digits is 26880, while the sum is 35.

The square root of 21865427 is about 4676.0482247299. The cubic root of 21865427 is about 279.6314325801.

The spelling of 21865427 in words is "twenty-one million, eight hundred sixty-five thousand, four hundred twenty-seven".