21672197 has 4 divisors (see below), whose sum is σ = 21785856. Its totient is φ = 21558540.

The previous prime is 21672191. The next prime is 21672221. The reversal of 21672197 is 79127612.

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 not a de Polignac number, because 21672197 - 2⁴ = 21672181 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 (21672191) 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, 56543 + ... + 56924.

It is an arithmetic number, because the mean of its divisors is an integer number (5446464).

Almost surely, 2^21672197 is an apocalyptic number.

It is an amenable number.

21672197 is a deficient number, since it is larger than the sum of its proper divisors (113659).

21672197 is a wasteful number, since it uses less digits than its factorization.

21672197 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 113658.

The product of its digits is 10584, while the sum is 35.

The square root of 21672197 is about 4655.3406964475. The cubic root of 21672197 is about 278.8052708676.

The spelling of 21672197 in words is "twenty-one million, six hundred seventy-two thousand, one hundred ninety-seven".