21897471 has 8 divisors (see below), whose sum is σ = 29525040. Its totient is φ = 14434112.

The previous prime is 21897433. The next prime is 21897493. The reversal of 21897471 is 17479812.

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 21897471 - 2¹⁴ = 21881087 is a prime.

It is a super-3 number, since 3×21897471³ (a number of 23 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21897431) 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, 40740 + ... + 41273.

It is an arithmetic number, because the mean of its divisors is an integer number (3690630).

Almost surely, 2^21897471 is an apocalyptic number.

21897471 is a deficient number, since it is larger than the sum of its proper divisors (7627569).

21897471 is an equidigital number, since it uses as much as digits as its factorization.

21897471 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 82105.

The product of its digits is 28224, while the sum is 39.

The square root of 21897471 is about 4679.4733678054. The cubic root of 21897471 is about 279.7679667831.

The spelling of 21897471 in words is "twenty-one million, eight hundred ninety-seven thousand, four hundred seventy-one".