21523743 has 6 divisors (see below), whose sum is σ = 31089864. Its totient is φ = 14349156.

The previous prime is 21523741. The next prime is 21523753. The reversal of 21523743 is 34732512.

It is not a de Polignac number, because 21523743 - 2¹ = 21523741 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21523741) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1195755 + ... + 1195772.

It is an arithmetic number, because the mean of its divisors is an integer number (5181644).

Almost surely, 2^21523743 is an apocalyptic number.

21523743 is a deficient number, since it is larger than the sum of its proper divisors (9566121).

21523743 is a wasteful number, since it uses less digits than its factorization.

21523743 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2391533 (or 2391530 counting only the distinct ones).

The product of its digits is 5040, while the sum is 27.

The square root of 21523743 is about 4639.3688148282. The cubic root of 21523743 is about 278.1672087268.

The spelling of 21523743 in words is "twenty-one million, five hundred twenty-three thousand, seven hundred forty-three".