21499471 has 4 divisors (see below), whose sum is σ = 24570832. Its totient is φ = 18428112.

The previous prime is 21499459. The next prime is 21499477. The reversal of 21499471 is 17499412.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21499471 - 2⁷ = 21499343 is a prime.

It is a super-3 number, since 3×21499471³ (a number of 23 digits) contains 333 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21499471.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21499477) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1535670 + ... + 1535683.

It is an arithmetic number, because the mean of its divisors is an integer number (6142708).

Almost surely, 2^21499471 is an apocalyptic number.

21499471 is a deficient number, since it is larger than the sum of its proper divisors (3071361).

21499471 is an equidigital number, since it uses as much as digits as its factorization.

21499471 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3071360.

The product of its digits is 18144, while the sum is 37.

The square root of 21499471 is about 4636.7522038599. The cubic root of 21499471 is about 278.0626077442.

The spelling of 21499471 in words is "twenty-one million, four hundred ninety-nine thousand, four hundred seventy-one".