21985473 has 4 divisors (see below), whose sum is σ = 29313968. Its totient is φ = 14656980.

The previous prime is 21985459. The next prime is 21985477. The reversal of 21985473 is 37458912.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 21985473 - 2¹⁰ = 21984449 is a prime.

It is a super-2 number, since 2×21985473² = 966722046067458, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21985477) 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 3 ways as a sum of consecutive naturals, for example, 3664243 + ... + 3664248.

It is an arithmetic number, because the mean of its divisors is an integer number (7328492).

Almost surely, 2^21985473 is an apocalyptic number.

It is an amenable number.

21985473 is a deficient number, since it is larger than the sum of its proper divisors (7328495).

21985473 is an equidigital number, since it uses as much as digits as its factorization.

21985473 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7328494.

The product of its digits is 60480, while the sum is 39.

The square root of 21985473 is about 4688.8669206963. The cubic root of 21985473 is about 280.1422449017.

The spelling of 21985473 in words is "twenty-one million, nine hundred eighty-five thousand, four hundred seventy-three".