21663427 has 2 divisors, whose sum is σ = 21663428. Its totient is φ = 21663426.

The previous prime is 21663419. The next prime is 21663431. The reversal of 21663427 is 72436612.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21663427 - 2³ = 21663419 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21663437) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10831713 + 10831714.

It is an arithmetic number, because the mean of its divisors is an integer number (10831714).

Almost surely, 2^21663427 is an apocalyptic number.

21663427 is a deficient number, since it is larger than the sum of its proper divisors (1).

21663427 is an equidigital number, since it uses as much as digits as its factorization.

21663427 is an evil number, because the sum of its binary digits is even.

The product of its digits is 12096, while the sum is 31.

The square root of 21663427 is about 4654.3986722239. The cubic root of 21663427 is about 278.7676581278.

The spelling of 21663427 in words is "twenty-one million, six hundred sixty-three thousand, four hundred twenty-seven".