21001221221146 has 16 divisors (see below), whose sum is σ = 31640773802688. Its totient is φ = 10454396760000.

The previous prime is 21001221221041. The next prime is 21001221221147. The reversal of 21001221221146 is 64112212210012.

It is a self number, because there is not a number n which added to its sum of digits gives 21001221221146.

It is not an unprimeable number, because it can be changed into a prime (21001221221147) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 24615030 + ... + 25453921.

It is an arithmetic number, because the mean of its divisors is an integer number (1977548362668).

Almost surely, 2^{21001221221146} is an apocalyptic number.

21001221221146 is a deficient number, since it is larger than the sum of its proper divisors (10639552581542).

21001221221146 is a wasteful number, since it uses less digits than its factorization.

21001221221146 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50069877.

The product of its (nonzero) digits is 768, while the sum is 25.

Adding to 21001221221146 its reverse (64112212210012), we get a palindrome (85113433431158).

The spelling of 21001221221146 in words is "twenty-one trillion, one billion, two hundred twenty-one million, two hundred twenty-one thousand, one hundred forty-six".