21131211042 has 32 divisors (see below), whose sum is σ = 47019403200. Its totient is φ = 7034563584.

The previous prime is 21131210983. The next prime is 21131211047. The reversal of 21131211042 is 24011213112.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is not an unprimeable number, because it can be changed into a prime (21131211047) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 212908 + ... + 295959.

It is an arithmetic number, because the mean of its divisors is an integer number (1469356350).

Almost surely, 2^21131211042 is an apocalyptic number.

21131211042 is an abundant number, since it is smaller than the sum of its proper divisors (25888192158).

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

21131211042 is a wasteful number, since it uses less digits than its factorization.

21131211042 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 509647 (or 509641 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 18.

Adding to 21131211042 its reverse (24011213112), we get a palindrome (45142424154).

The spelling of 21131211042 in words is "twenty-one billion, one hundred thirty-one million, two hundred eleven thousand, forty-two".