21742759 has 4 divisors (see below), whose sum is σ = 21764880. Its totient is φ = 21720640.

The previous prime is 21742757. The next prime is 21742771. The reversal of 21742759 is 95724712.

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 21742759 - 2¹ = 21742757 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 (21742753) 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 3 ways as a sum of consecutive naturals, for example, 9514 + ... + 11575.

It is an arithmetic number, because the mean of its divisors is an integer number (5441220).

Almost surely, 2^21742759 is an apocalyptic number.

21742759 is a deficient number, since it is larger than the sum of its proper divisors (22121).

21742759 is a wasteful number, since it uses less digits than its factorization.

21742759 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22120.

The product of its digits is 35280, while the sum is 37.

The square root of 21742759 is about 4662.9131452344. The cubic root of 21742759 is about 279.1075282567.

The spelling of 21742759 in words is "twenty-one million, seven hundred forty-two thousand, seven hundred fifty-nine".