21131471 has 8 divisors (see below), whose sum is σ = 21598704. Its totient is φ = 20666880.

The previous prime is 21131449. The next prime is 21131489. The reversal of 21131471 is 17413112.

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 a de Polignac number, because none of the positive numbers 2^k-21131471 is a prime.

It is a super-3 number, since 3×21131471³ (a number of 23 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21131771) 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, 30236 + ... + 30926.

It is an arithmetic number, because the mean of its divisors is an integer number (2699838).

Almost surely, 2^21131471 is an apocalyptic number.

21131471 is a deficient number, since it is larger than the sum of its proper divisors (467233).

21131471 is an equidigital number, since it uses as much as digits as its factorization.

21131471 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1321.

The product of its digits is 168, while the sum is 20.

The square root of 21131471 is about 4596.8979758093. The cubic root of 21131471 is about 276.4669639971.

Adding to 21131471 its reverse (17413112), we get a palindrome (38544583).

The spelling of 21131471 in words is "twenty-one million, one hundred thirty-one thousand, four hundred seventy-one".