21000221221985 has 16 divisors (see below), whose sum is σ = 27134882064000. Its totient is φ = 15543932434176.

The previous prime is 21000221221979. The next prime is 21000221222033. The reversal of 21000221221985 is 58912212200012.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21000221221985 - 2⁶ = 21000221221921 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2093735885 + ... + 2093745914.

It is an arithmetic number, because the mean of its divisors is an integer number (1695930129000).

Almost surely, 2^{21000221221985} is an apocalyptic number.

It is an amenable number.

21000221221985 is a deficient number, since it is larger than the sum of its proper divisors (6134660842015).

21000221221985 is a wasteful number, since it uses less digits than its factorization.

21000221221985 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4187481880.

The product of its (nonzero) digits is 11520, while the sum is 35.

Adding to 21000221221985 its reverse (58912212200012), we get a palindrome (79912433421997).

The spelling of 21000221221985 in words is "twenty-one trillion, two hundred twenty-one million, two hundred twenty-one thousand, nine hundred eighty-five".