21917071 has 8 divisors (see below), whose sum is σ = 23999184. Its totient is φ = 19849920.

The previous prime is 21917023. The next prime is 21917113. The reversal of 21917071 is 17071912.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21917071 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21917171) 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, 550 + ... + 6643.

It is an arithmetic number, because the mean of its divisors is an integer number (2999898).

Almost surely, 2^21917071 is an apocalyptic number.

21917071 is a deficient number, since it is larger than the sum of its proper divisors (2082113).

21917071 is a wasteful number, since it uses less digits than its factorization.

21917071 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7481.

The product of its (nonzero) digits is 882, while the sum is 28.

The square root of 21917071 is about 4681.5671521404. The cubic root of 21917071 is about 279.8514135111.

Adding to 21917071 its reverse (17071912), we get a palindrome (38988983).

The spelling of 21917071 in words is "twenty-one million, nine hundred seventeen thousand, seventy-one".