21697863 has 16 divisors (see below), whose sum is σ = 31996416. Its totient is φ = 12968640.

The previous prime is 21697853. The next prime is 21697889. The reversal of 21697863 is 36879612.

It is a happy number.

It is not a de Polignac number, because 21697863 - 2⁴ = 21697847 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21697853) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2095 + ... + 6912.

It is an arithmetic number, because the mean of its divisors is an integer number (1999776).

Almost surely, 2^21697863 is an apocalyptic number.

21697863 is a deficient number, since it is larger than the sum of its proper divisors (10298553).

21697863 is a wasteful number, since it uses less digits than its factorization.

21697863 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9094.

The product of its digits is 108864, while the sum is 42.

The square root of 21697863 is about 4658.0964996445. The cubic root of 21697863 is about 278.9152888337.

The spelling of 21697863 in words is "twenty-one million, six hundred ninety-seven thousand, eight hundred sixty-three".