21572743 has 4 divisors (see below), whose sum is σ = 21603880. Its totient is φ = 21541608.

The previous prime is 21572729. The next prime is 21572753. The reversal of 21572743 is 34727512.

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 21572743 - 2⁹ = 21572231 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 (21572753) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 14505 + ... + 15922.

It is an arithmetic number, because the mean of its divisors is an integer number (5400970).

Almost surely, 2^21572743 is an apocalyptic number.

21572743 is a deficient number, since it is larger than the sum of its proper divisors (31137).

21572743 is an equidigital number, since it uses as much as digits as its factorization.

21572743 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31136.

The product of its digits is 11760, while the sum is 31.

The square root of 21572743 is about 4644.6467034641. The cubic root of 21572743 is about 278.3781364604.

It can be divided in two parts, 2157 and 2743, that added together give a square (4900 = 70²).

The spelling of 21572743 in words is "twenty-one million, five hundred seventy-two thousand, seven hundred forty-three".