21672191 has 2 divisors, whose sum is σ = 21672192. Its totient is φ = 21672190.

The previous prime is 21672181. The next prime is 21672221. The reversal of 21672191 is 19127612.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21672191 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21672151) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10836095 + 10836096.

It is an arithmetic number, because the mean of its divisors is an integer number (10836096).

Almost surely, 2^21672191 is an apocalyptic number.

21672191 is a deficient number, since it is larger than the sum of its proper divisors (1).

21672191 is an equidigital number, since it uses as much as digits as its factorization.

21672191 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1512, while the sum is 29.

The square root of 21672191 is about 4655.3400520263. The cubic root of 21672191 is about 278.8052451383.

The spelling of 21672191 in words is "twenty-one million, six hundred seventy-two thousand, one hundred ninety-one".