21706861 has 8 divisors (see below), whose sum is σ = 24034464.
Its totient is φ = 19438320.
The previous prime is 21706837. The next prime is 21706889. The reversal of 21706861 is 16860712.
It is a sphenic number, since it is the product of 3 distinct primes.
It is not a de Polignac number, because 21706861 - 217 = 21575789 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 (21706891) 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, 13990 + ... + 15463.
It is an arithmetic number, because the mean of its divisors is an integer number (3004308).
Almost surely, 221706861 is an apocalyptic number.
It is an amenable number.
21706861 is a deficient number, since it is larger than the sum of its proper divisors (2327603).
21706861 is a wasteful number, since it uses less digits than its factorization.
It is an anagram of its base 11 representation: 21706861 = (11286760)11.
21706861 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 29531.
The product of its (nonzero) digits is 4032, while the sum is 31.
The square root of 21706861 is about 4659.0622447012.
The cubic root of 21706861 is about 278.9538384508.
The spelling of 21706861 in words is "twenty-one million, seven hundred six thousand, eight hundred sixty-one".