21243973 has 8 divisors (see below), whose sum is σ = 22320000. Its totient is φ = 20180688.

The previous prime is 21243941. The next prime is 21243977. The reversal of 21243973 is 37934212.

21243973 is nontrivially palindromic in base 2.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21243973 - 2⁵ = 21243941 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21243977) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 328 + ... + 6526.

It is an arithmetic number, because the mean of its divisors is an integer number (2790000).

Almost surely, 2^21243973 is an apocalyptic number.

21243973 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

It is an amenable number.

21243973 is a deficient number, since it is larger than the sum of its proper divisors (1076027).

21243973 is a wasteful number, since it uses less digits than its factorization.

21243973 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6371.

The product of its digits is 9072, while the sum is 31.

The square root of 21243973 is about 4609.1184623526. The cubic root of 21243973 is about 276.9567240712.

The spelling of 21243973 in words is "twenty-one million, two hundred forty-three thousand, nine hundred seventy-three".