21740686 has 8 divisors (see below), whose sum is σ = 35575704. Its totient is φ = 9882120.

The previous prime is 21740683. The next prime is 21740687. The reversal of 21740686 is 68604712.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21740683) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 494085 + ... + 494128.

It is an arithmetic number, because the mean of its divisors is an integer number (4446963).

Almost surely, 2^21740686 is an apocalyptic number.

21740686 is a deficient number, since it is larger than the sum of its proper divisors (13835018).

21740686 is a wasteful number, since it uses less digits than its factorization.

21740686 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 988226.

The product of its (nonzero) digits is 16128, while the sum is 34.

The square root of 21740686 is about 4662.6908540027. The cubic root of 21740686 is about 279.0986577435.

The spelling of 21740686 in words is "twenty-one million, seven hundred forty thousand, six hundred eighty-six".