21971919 has 8 divisors (see below), whose sum is σ = 29347200. Its totient is φ = 14622296.

The previous prime is 21971903. The next prime is 21971927. The reversal of 21971919 is 91917912.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21971919 - 2⁴ = 21971903 is a prime.

It is a super-2 number, since 2×21971919² = 965530449085122, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21971119) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4317 + ... + 7910.

It is an arithmetic number, because the mean of its divisors is an integer number (3668400).

Almost surely, 2^21971919 is an apocalyptic number.

21971919 is a deficient number, since it is larger than the sum of its proper divisors (7375281).

21971919 is a wasteful number, since it uses less digits than its factorization.

21971919 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12829.

The product of its digits is 10206, while the sum is 39.

The square root of 21971919 is about 4687.4213593403. The cubic root of 21971919 is about 280.0846640233.

The spelling of 21971919 in words is "twenty-one million, nine hundred seventy-one thousand, nine hundred nineteen".