21012885 has 32 divisors (see below), whose sum is σ = 38568960. Its totient is φ = 10843200.

The previous prime is 21012883. The next prime is 21012889. The reversal of 21012885 is 58821012.

It is not a de Polignac number, because 21012885 - 2¹ = 21012883 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21012883) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1675 + ... + 6695.

It is an arithmetic number, because the mean of its divisors is an integer number (1205280).

Almost surely, 2^21012885 is an apocalyptic number.

It is an amenable number.

21012885 is a deficient number, since it is larger than the sum of its proper divisors (17556075).

21012885 is a wasteful number, since it uses less digits than its factorization.

21012885 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5066 (or 5060 counting only the distinct ones).

The product of its (nonzero) digits is 1280, while the sum is 27.

The square root of 21012885 is about 4583.9813481296. The cubic root of 21012885 is about 275.9488326697.

Adding to 21012885 its reverse (58821012), we get a palindrome (79833897).

The spelling of 21012885 in words is "twenty-one million, twelve thousand, eight hundred eighty-five".