21706669 has 4 divisors (see below), whose sum is σ = 21726144. Its totient is φ = 21687196.

The previous prime is 21706639. The next prime is 21706693. The reversal of 21706669 is 96660712.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21706669 is a prime.

It is a super-2 number, since 2×21706669² = 942358958151122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21706609) 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, 7957 + ... + 10330.

It is an arithmetic number, because the mean of its divisors is an integer number (5431536).

Almost surely, 2^21706669 is an apocalyptic number.

It is an amenable number.

21706669 is a deficient number, since it is larger than the sum of its proper divisors (19475).

21706669 is a wasteful number, since it uses less digits than its factorization.

21706669 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19474.

The product of its (nonzero) digits is 27216, while the sum is 37.

The square root of 21706669 is about 4659.0416396508. The cubic root of 21706669 is about 278.9530159874.

The spelling of 21706669 in words is "twenty-one million, seven hundred six thousand, six hundred sixty-nine".