19664971 has 8 divisors (see below), whose sum is σ = 20861280. Its totient is φ = 18473088.

The previous prime is 19664951. The next prime is 19664993. The reversal of 19664971 is 17946691.

It is a happy number.

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 19664971 - 2¹⁵ = 19632203 is a prime.

It is a super-2 number, since 2×19664971² = 773422168861682, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (19664951) 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, 14250 + ... + 15568.

It is an arithmetic number, because the mean of its divisors is an integer number (2607660).

Almost surely, 2^19664971 is an apocalyptic number.

19664971 is a deficient number, since it is larger than the sum of its proper divisors (1196309).

19664971 is a wasteful number, since it uses less digits than its factorization.

19664971 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2213.

The product of its digits is 81648, while the sum is 43.

The square root of 19664971 is about 4434.5203799284. The cubic root of 19664971 is about 269.9175376888.

The spelling of 19664971 in words is "nineteen million, six hundred sixty-four thousand, nine hundred seventy-one".