21970191 has 4 divisors (see below), whose sum is σ = 29293592. Its totient is φ = 14646792.

The previous prime is 21970189. The next prime is 21970229. The reversal of 21970191 is 19107912.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 21970191 - 2¹ = 21970189 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 (21970121) 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, 3661696 + ... + 3661701.

It is an arithmetic number, because the mean of its divisors is an integer number (7323398).

Almost surely, 2^21970191 is an apocalyptic number.

21970191 is a deficient number, since it is larger than the sum of its proper divisors (7323401).

21970191 is an equidigital number, since it uses as much as digits as its factorization.

21970191 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7323400.

The product of its (nonzero) digits is 1134, while the sum is 30.

The square root of 21970191 is about 4687.2370326238. The cubic root of 21970191 is about 280.0773213330.

The spelling of 21970191 in words is "twenty-one million, nine hundred seventy thousand, one hundred ninety-one".