21319971 has 8 divisors (see below), whose sum is σ = 29343744. Its totient is φ = 13754760.

The previous prime is 21319937. The next prime is 21319979. The reversal of 21319971 is 17991312.

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

It is not a de Polignac number, because 21319971 - 2¹⁴ = 21303587 is a prime.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (21319979) 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, 114531 + ... + 114716.

It is an arithmetic number, because the mean of its divisors is an integer number (3667968).

Almost surely, 2^21319971 is an apocalyptic number.

21319971 is a deficient number, since it is larger than the sum of its proper divisors (8023773).

21319971 is a wasteful number, since it uses less digits than its factorization.

21319971 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 229281.

The product of its digits is 3402, while the sum is 33.

The square root of 21319971 is about 4617.3554119214. The cubic root of 21319971 is about 277.2865918682.

The spelling of 21319971 in words is "twenty-one million, three hundred nineteen thousand, nine hundred seventy-one".