21201121144 has 16 divisors (see below), whose sum is σ = 45430974000. Its totient is φ = 9086194752.

The previous prime is 21201121129. The next prime is 21201121157. The reversal of 21201121144 is 44112110212.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 189295669 + ... + 189295780.

It is an arithmetic number, because the mean of its divisors is an integer number (2839435875).

Almost surely, 2^21201121144 is an apocalyptic number.

It is an amenable number.

21201121144 is an abundant number, since it is smaller than the sum of its proper divisors (24229852856).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21201121144 is a wasteful number, since it uses less digits than its factorization.

21201121144 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 378591462 (or 378591458 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 19.

Adding to 21201121144 its reverse (44112110212), we get a palindrome (65313231356).

The spelling of 21201121144 in words is "twenty-one billion, two hundred one million, one hundred twenty-one thousand, one hundred forty-four".