21819471 has 12 divisors (see below), whose sum is σ = 29433672. Its totient is φ = 14377728.

The previous prime is 21819463. The next prime is 21819521. The reversal of 21819471 is 17491812.

It is not a de Polignac number, because 21819471 - 2³ = 21819463 is a prime.

It is a super-3 number, since 3×21819471³ (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 (21819461) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 27841 + ... + 28613.

It is an arithmetic number, because the mean of its divisors is an integer number (2452806).

Almost surely, 2^21819471 is an apocalyptic number.

21819471 is a deficient number, since it is larger than the sum of its proper divisors (7614201).

21819471 is an frugal number, since it uses more digits than its factorization.

21819471 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 970 (or 873 counting only the distinct ones).

The product of its digits is 4032, while the sum is 33.

The square root of 21819471 is about 4671.1316615998. The cubic root of 21819471 is about 279.4353886043.

The spelling of 21819471 in words is "twenty-one million, eight hundred nineteen thousand, four hundred seventy-one".