21403943 has 16 divisors (see below), whose sum is σ = 24343200. Its totient is φ = 18641280.

The previous prime is 21403931. The next prime is 21403973. The reversal of 21403943 is 34930412.

It is a cyclic number.

It is not a de Polignac number, because 21403943 - 2⁸ = 21403687 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 (21403903) 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, 72905 + ... + 73197.

It is an arithmetic number, because the mean of its divisors is an integer number (1521450).

Almost surely, 2^21403943 is an apocalyptic number.

21403943 is a deficient number, since it is larger than the sum of its proper divisors (2939257).

21403943 is a wasteful number, since it uses less digits than its factorization.

21403943 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 562.

The product of its (nonzero) digits is 2592, while the sum is 26.

The square root of 21403943 is about 4626.4395597479. The cubic root of 21403943 is about 277.6501603238.

The spelling of 21403943 in words is "twenty-one million, four hundred three thousand, nine hundred forty-three".