21099863 has 2 divisors, whose sum is σ = 21099864. Its totient is φ = 21099862.

The previous prime is 21099833. The next prime is 21099887. The reversal of 21099863 is 36899012.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21099863 - 2¹⁰ = 21098839 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21099833) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10549931 + 10549932.

It is an arithmetic number, because the mean of its divisors is an integer number (10549932).

Almost surely, 2^21099863 is an apocalyptic number.

21099863 is a deficient number, since it is larger than the sum of its proper divisors (1).

21099863 is an equidigital number, since it uses as much as digits as its factorization.

21099863 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 23328, while the sum is 38.

The square root of 21099863 is about 4593.4587186563. The cubic root of 21099863 is about 276.3290507647.

The spelling of 21099863 in words is "twenty-one million, ninety-nine thousand, eight hundred sixty-three".