21695861 has 8 divisors (see below), whose sum is σ = 23709504. Its totient is φ = 19689120.

The previous prime is 21695837. The next prime is 21695879. The reversal of 21695861 is 16859612.

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

It is not a de Polignac number, because 21695861 - 2¹⁰ = 21694837 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 (21695561) 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 7 ways as a sum of consecutive naturals, for example, 6641 + ... + 9353.

It is an arithmetic number, because the mean of its divisors is an integer number (2963688).

Almost surely, 2^21695861 is an apocalyptic number.

It is an amenable number.

21695861 is a deficient number, since it is larger than the sum of its proper divisors (2013643).

21695861 is a wasteful number, since it uses less digits than its factorization.

21695861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3451.

The product of its digits is 25920, while the sum is 38.

The square root of 21695861 is about 4657.8816000409. The cubic root of 21695861 is about 278.9067103302.

The spelling of 21695861 in words is "twenty-one million, six hundred ninety-five thousand, eight hundred sixty-one".