21673863 has 12 divisors (see below), whose sum is σ = 31366608. Its totient is φ = 14421600.

The previous prime is 21673859. The next prime is 21673921. The reversal of 21673863 is 36837612.

It is a happy number.

It is not a de Polignac number, because 21673863 - 2² = 21673859 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21673163) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3406 + ... + 7412.

It is an arithmetic number, because the mean of its divisors is an integer number (2613884).

Almost surely, 2^21673863 is an apocalyptic number.

21673863 is a deficient number, since it is larger than the sum of its proper divisors (9692745).

21673863 is a wasteful number, since it uses less digits than its factorization.

21673863 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4614 (or 4611 counting only the distinct ones).

The product of its digits is 36288, while the sum is 36.

The square root of 21673863 is about 4655.5196272811. The cubic root of 21673863 is about 278.8124148546.

The spelling of 21673863 in words is "twenty-one million, six hundred seventy-three thousand, eight hundred sixty-three".