21403863 has 24 divisors (see below), whose sum is σ = 33852000. Its totient is φ = 12951360.

The previous prime is 21403849. The next prime is 21403883. The reversal of 21403863 is 36830412.

It is a happy number.

It is not a de Polignac number, because 21403863 - 2⁵ = 21403831 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21403813) 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 in 23 ways as a sum of consecutive naturals, for example, 5638 + ... + 8636.

It is an arithmetic number, because the mean of its divisors is an integer number (1410500).

Almost surely, 2^21403863 is an apocalyptic number.

21403863 is a deficient number, since it is larger than the sum of its proper divisors (12448137).

21403863 is a wasteful number, since it uses less digits than its factorization.

21403863 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3079 (or 3076 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 27.

The square root of 21403863 is about 4626.4309137822. The cubic root of 21403863 is about 277.6498144056.

The spelling of 21403863 in words is "twenty-one million, four hundred three thousand, eight hundred sixty-three".