21403811 has 16 divisors (see below), whose sum is σ = 25374048. Its totient is φ = 17946720.

The previous prime is 21403801. The next prime is 21403813. The reversal of 21403811 is 11830412.

It is a de Polignac number, because none of the positive numbers 2^k-21403811 is a prime.

It is a Duffinian 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 (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 16685 + ... + 17921.

It is an arithmetic number, because the mean of its divisors is an integer number (1585878).

Almost surely, 2^21403811 is an apocalyptic number.

21403811 is a deficient number, since it is larger than the sum of its proper divisors (3970237).

21403811 is a wasteful number, since it uses less digits than its factorization.

21403811 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1283 (or 1261 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 20.

The square root of 21403811 is about 4626.4252938959. The cubic root of 21403811 is about 277.6495895583.

The spelling of 21403811 in words is "twenty-one million, four hundred three thousand, eight hundred eleven".