21081902 has 8 divisors (see below), whose sum is σ = 31675800. Its totient is φ = 10523304.

The previous prime is 21081901. The next prime is 21081919. The reversal of 21081902 is 20918012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21081901) 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, 7277 + ... + 9752.

It is an arithmetic number, because the mean of its divisors is an integer number (3959475).

Almost surely, 2^21081902 is an apocalyptic number.

21081902 is a deficient number, since it is larger than the sum of its proper divisors (10593898).

21081902 is a wasteful number, since it uses less digits than its factorization.

21081902 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17650.

The product of its (nonzero) digits is 288, while the sum is 23.

The square root of 21081902 is about 4591.5032396809. The cubic root of 21081902 is about 276.2506212663.

Adding to 21081902 its reverse (20918012), we get a palindrome (41999914).

The spelling of 21081902 in words is "twenty-one million, eighty-one thousand, nine hundred two".