21699871 has 8 divisors (see below), whose sum is σ = 23598000. Its totient is φ = 19870848.

The previous prime is 21699869. The next prime is 21699883. The reversal of 21699871 is 17899612.

21699871 is nontrivially palindromic in base 15.

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 21699871 - 2¹ = 21699869 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 (21699071) 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, 16621 + ... + 17878.

It is an arithmetic number, because the mean of its divisors is an integer number (2949750).

Almost surely, 2^21699871 is an apocalyptic number.

21699871 is a deficient number, since it is larger than the sum of its proper divisors (1898129).

21699871 is a wasteful number, since it uses less digits than its factorization.

21699871 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34553.

The product of its digits is 54432, while the sum is 43.

The square root of 21699871 is about 4658.3120333443. The cubic root of 21699871 is about 278.9238925170.

The spelling of 21699871 in words is "twenty-one million, six hundred ninety-nine thousand, eight hundred seventy-one".