21743661 has 8 divisors (see below), whose sum is σ = 29015424. Its totient is φ = 14483840.

The previous prime is 21743651. The next prime is 21743677. The reversal of 21743661 is 16634712.

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

It is a cyclic number.

It is not a de Polignac number, because 21743661 - 2¹¹ = 21741613 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21743611) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2956 + ... + 7226.

It is an arithmetic number, because the mean of its divisors is an integer number (3626928).

Almost surely, 2^21743661 is an apocalyptic number.

It is an amenable number.

21743661 is a deficient number, since it is larger than the sum of its proper divisors (7271763).

21743661 is a wasteful number, since it uses less digits than its factorization.

21743661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5971.

The product of its digits is 6048, while the sum is 30.

The square root of 21743661 is about 4663.0098648834. The cubic root of 21743661 is about 279.1113878023. Note that the first 3 decimals are identical.

The spelling of 21743661 in words is "twenty-one million, seven hundred forty-three thousand, six hundred sixty-one".