21913043 has 4 divisors (see below), whose sum is σ = 22865808. Its totient is φ = 20960280.

The previous prime is 21913039. The next prime is 21913049. The reversal of 21913043 is 34031912.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21913043 - 2² = 21913039 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (23), and also a Moran number because the ratio is a prime number: 952741 = 21913043 / (2 + 1 + 9 + 1 + 3 + 0 + 4 + 3).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21913049) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 476348 + ... + 476393.

It is an arithmetic number, because the mean of its divisors is an integer number (5716452).

Almost surely, 2^21913043 is an apocalyptic number.

21913043 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

21913043 is a deficient number, since it is larger than the sum of its proper divisors (952765).

21913043 is an equidigital number, since it uses as much as digits as its factorization.

21913043 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 952764.

The product of its (nonzero) digits is 648, while the sum is 23.

The square root of 21913043 is about 4681.1369345491. The cubic root of 21913043 is about 279.8342684197.

Adding to 21913043 its reverse (34031912), we get a palindrome (55944955).

The spelling of 21913043 in words is "twenty-one million, nine hundred thirteen thousand, forty-three".