21099427 has 2 divisors, whose sum is σ = 21099428. Its totient is φ = 21099426.

The previous prime is 21099413. The next prime is 21099451. The reversal of 21099427 is 72499012.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21099427 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21099392 and 21099401.

It is not a weakly prime, because it can be changed into another prime (21099467) 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, 10549713 + 10549714.

It is an arithmetic number, because the mean of its divisors is an integer number (10549714).

Almost surely, 2^21099427 is an apocalyptic number.

21099427 is a deficient number, since it is larger than the sum of its proper divisors (1).

21099427 is an equidigital number, since it uses as much as digits as its factorization.

21099427 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 9072, while the sum is 34.

The square root of 21099427 is about 4593.4112596196. The cubic root of 21099427 is about 276.3271474302.

The spelling of 21099427 in words is "twenty-one million, ninety-nine thousand, four hundred twenty-seven".