21238471 has 2 divisors, whose sum is σ = 21238472. Its totient is φ = 21238470.

The previous prime is 21238433. The next prime is 21238487. The reversal of 21238471 is 17483212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21238471 - 2¹⁵ = 21205703 is a prime.

It is a super-3 number, since 3×21238471³ (a number of 23 digits) contains 333 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21238271) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10619235 + 10619236.

It is an arithmetic number, because the mean of its divisors is an integer number (10619236).

Almost surely, 2^21238471 is an apocalyptic number.

21238471 is a deficient number, since it is larger than the sum of its proper divisors (1).

21238471 is an equidigital number, since it uses as much as digits as its factorization.

21238471 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2688, while the sum is 28.

The square root of 21238471 is about 4608.5215633650. The cubic root of 21238471 is about 276.9328122310.

It can be divided in two parts, 212 and 38471, that added together give a palindrome (38683).

The spelling of 21238471 in words is "twenty-one million, two hundred thirty-eight thousand, four hundred seventy-one".