21972043 has 4 divisors (see below), whose sum is σ = 22565920. Its totient is φ = 21378168.

The previous prime is 21972031. The next prime is 21972073. The reversal of 21972043 is 34027912.

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 21972043 - 2²¹ = 19874891 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21972073) 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, 296883 + ... + 296956.

It is an arithmetic number, because the mean of its divisors is an integer number (5641480).

Almost surely, 2^21972043 is an apocalyptic number.

21972043 is a deficient number, since it is larger than the sum of its proper divisors (593877).

21972043 is an equidigital number, since it uses as much as digits as its factorization.

21972043 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 593876.

The product of its (nonzero) digits is 3024, while the sum is 28.

The square root of 21972043 is about 4687.4345862102. The cubic root of 21972043 is about 280.0851909145.

Adding to 21972043 its reverse (34027912), we get a palindrome (55999955).

The spelling of 21972043 in words is "twenty-one million, nine hundred seventy-two thousand, forty-three".