21418943 has 16 divisors (see below), whose sum is σ = 26865216. Its totient is φ = 16623360.

The previous prime is 21418937. The next prime is 21418951. The reversal of 21418943 is 34981412.

It is a happy number.

It is not a de Polignac number, because 21418943 - 2²⁰ = 20370367 is a prime.

It is a super-2 number, since 2×21418943² = 917542238474498, which contains 22 as substring.

It is a Smith number, since the sum of its digits (32) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an alternating number because its digits alternate between even and odd.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21408943) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2603 + ... + 7043.

It is an arithmetic number, because the mean of its divisors is an integer number (1679076).

Almost surely, 2^21418943 is an apocalyptic number.

21418943 is a deficient number, since it is larger than the sum of its proper divisors (5446273).

21418943 is a wasteful number, since it uses less digits than its factorization.

21418943 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4514.

The product of its digits is 6912, while the sum is 32.

The square root of 21418943 is about 4628.0603928644. The cubic root of 21418943 is about 277.7150047606.

The spelling of 21418943 in words is "twenty-one million, four hundred eighteen thousand, nine hundred forty-three".