21521131142 has 24 divisors (see below), whose sum is σ = 39184885296. Its totient is φ = 8822326128.

The previous prime is 21521131123. The next prime is 21521131193. The reversal of 21521131142 is 24113112512.

It is a Harshad number since it is a multiple of its sum of digits (23).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4771733 + ... + 4776240.

It is an arithmetic number, because the mean of its divisors is an integer number (1632703554).

Almost surely, 2^21521131142 is an apocalyptic number.

21521131142 is a deficient number, since it is larger than the sum of its proper divisors (17663754154).

21521131142 is a wasteful number, since it uses less digits than its factorization.

21521131142 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9548012 (or 9548005 counting only the distinct ones).

The product of its digits is 480, while the sum is 23.

Adding to 21521131142 its reverse (24113112512), we get a palindrome (45634243654).

The spelling of 21521131142 in words is "twenty-one billion, five hundred twenty-one million, one hundred thirty-one thousand, one hundred forty-two".