21031212042 has 24 divisors (see below), whose sum is σ = 45571202820. Its totient is φ = 7009853760.

The previous prime is 21031212011. The next prime is 21031212049. The reversal of 21031212042 is 24021213012.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 19942805961 + 1088406081 = 141219^2 + 32991^2 .

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 (21031212049) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 236992 + ... + 313412.

Almost surely, 2^21031212042 is an apocalyptic number.

21031212042 is an abundant number, since it is smaller than the sum of its proper divisors (24539990778).

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

21031212042 is a wasteful number, since it uses less digits than its factorization.

21031212042 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 91718 (or 91715 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 18.

Adding to 21031212042 its reverse (24021213012), we get a palindrome (45052425054).

The spelling of 21031212042 in words is "twenty-one billion, thirty-one million, two hundred twelve thousand, forty-two".