21385471 has 2 divisors, whose sum is σ = 21385472. Its totient is φ = 21385470.

The previous prime is 21385459. The next prime is 21385513. The reversal of 21385471 is 17458312.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21385471 - 2¹¹ = 21383423 is a prime.

It is a super-3 number, since 3×21385471³ (a number of 23 digits) contains 333 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21385411) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10692735 + 10692736.

It is an arithmetic number, because the mean of its divisors is an integer number (10692736).

Almost surely, 2^21385471 is an apocalyptic number.

21385471 is a deficient number, since it is larger than the sum of its proper divisors (1).

21385471 is an equidigital number, since it uses as much as digits as its factorization.

21385471 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6720, while the sum is 31.

The square root of 21385471 is about 4624.4427772435. The cubic root of 21385471 is about 277.5702649221.

The spelling of 21385471 in words is "twenty-one million, three hundred eighty-five thousand, four hundred seventy-one".