21132197 has 2 divisors, whose sum is σ = 21132198. Its totient is φ = 21132196.

The previous prime is 21132191. The next prime is 21132211. The reversal of 21132197 is 79123112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20802721 + 329476 = 4561^2 + 574^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21132197 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21132191) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10566098 + 10566099.

It is an arithmetic number, because the mean of its divisors is an integer number (10566099).

Almost surely, 2^21132197 is an apocalyptic number.

It is an amenable number.

21132197 is a deficient number, since it is larger than the sum of its proper divisors (1).

21132197 is an equidigital number, since it uses as much as digits as its factorization.

21132197 is an evil number, because the sum of its binary digits is even.

The product of its digits is 756, while the sum is 26.

The square root of 21132197 is about 4596.9769414257. The cubic root of 21132197 is about 276.4701300918.

The spelling of 21132197 in words is "twenty-one million, one hundred thirty-two thousand, one hundred ninety-seven".