21686061 has 8 divisors (see below), whose sum is σ = 29587360. Its totient is φ = 14121072.

The previous prime is 21686057. The next prime is 21686111. The reversal of 21686061 is 16068612.

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

It is not a de Polignac number, because 21686061 - 2² = 21686057 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21681061) 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, 83926 + ... + 84183.

It is an arithmetic number, because the mean of its divisors is an integer number (3698420).

Almost surely, 2^21686061 is an apocalyptic number.

It is an amenable number.

21686061 is a deficient number, since it is larger than the sum of its proper divisors (7901299).

21686061 is a wasteful number, since it uses less digits than its factorization.

21686061 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 168155.

The product of its (nonzero) digits is 3456, while the sum is 30.

The square root of 21686061 is about 4656.8295008514. The cubic root of 21686061 is about 278.8647100395.

The spelling of 21686061 in words is "twenty-one million, six hundred eighty-six thousand, sixty-one".