21740689 has 4 divisors (see below), whose sum is σ = 21818340. Its totient is φ = 21663040.

The previous prime is 21740687. The next prime is 21740711. The reversal of 21740689 is 98604712.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 5475600 + 16265089 = 2340^2 + 4033^2 .

It is a cyclic number.

It is not a de Polignac number, because 21740689 - 2¹ = 21740687 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21740683) 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, 38404 + ... + 38965.

It is an arithmetic number, because the mean of its divisors is an integer number (5454585).

Almost surely, 2^21740689 is an apocalyptic number.

It is an amenable number.

21740689 is a deficient number, since it is larger than the sum of its proper divisors (77651).

21740689 is an equidigital number, since it uses as much as digits as its factorization.

21740689 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 77650.

The product of its (nonzero) digits is 24192, while the sum is 37.

The square root of 21740689 is about 4662.6911757053. The cubic root of 21740689 is about 279.0986705811.

The spelling of 21740689 in words is "twenty-one million, seven hundred forty thousand, six hundred eighty-nine".