21743645 has 16 divisors (see below), whose sum is σ = 32531328. Its totient is φ = 13554240.

The previous prime is 21743641. The next prime is 21743651. The reversal of 21743645 is 54634712.

It is not a de Polignac number, because 21743645 - 2² = 21743641 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21743641) 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, 27854 + ... + 28623.

It is an arithmetic number, because the mean of its divisors is an integer number (2033208).

Almost surely, 2^21743645 is an apocalyptic number.

It is an amenable number.

21743645 is a deficient number, since it is larger than the sum of its proper divisors (10787683).

21743645 is a wasteful number, since it uses less digits than its factorization.

21743645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56500.

The product of its digits is 20160, while the sum is 32.

The square root of 21743645 is about 4663.0081492530. The cubic root of 21743645 is about 279.1113193412. Note that the first 3 decimals are identical.

The spelling of 21743645 in words is "twenty-one million, seven hundred forty-three thousand, six hundred forty-five".