21071885 has 4 divisors (see below), whose sum is σ = 25286268. Its totient is φ = 16857504.

The previous prime is 21071881. The next prime is 21071903. The reversal of 21071885 is 58817012.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 4919524 + 16152361 = 2218^2 + 4019^2 .

It is a cyclic number.

It is not a de Polignac number, because 21071885 - 2² = 21071881 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21071881) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2107184 + ... + 2107193.

It is an arithmetic number, because the mean of its divisors is an integer number (6321567).

Almost surely, 2^21071885 is an apocalyptic number.

It is an amenable number.

21071885 is a deficient number, since it is larger than the sum of its proper divisors (4214383).

21071885 is an equidigital number, since it uses as much as digits as its factorization.

21071885 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4214382.

The product of its (nonzero) digits is 4480, while the sum is 32.

The square root of 21071885 is about 4590.4122908514. The cubic root of 21071885 is about 276.2068611276.

Adding to 21071885 its reverse (58817012), we get a palindrome (79888897).

The spelling of 21071885 in words is "twenty-one million, seventy-one thousand, eight hundred eighty-five".