21251051442 has 24 divisors (see below), whose sum is σ = 46164178944. Its totient is φ = 7065186264.

The previous prime is 21251051431. The next prime is 21251051443. The reversal of 21251051442 is 24415015212.

It is a happy number.

21251051442 is a `hidden beast` number, since 2 + 1 + 2 + 510 + 5 + 144 + 2 = 666.

It is not an unprimeable number, because it can be changed into a prime (21251051443) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1534378 + ... + 1548165.

It is an arithmetic number, because the mean of its divisors is an integer number (1923507456).

Almost surely, 2^21251051442 is an apocalyptic number.

21251051442 is an abundant number, since it is smaller than the sum of its proper divisors (24913127502).

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

21251051442 is a wasteful number, since it uses less digits than its factorization.

21251051442 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3082934 (or 3082931 counting only the distinct ones).

The product of its (nonzero) digits is 3200, while the sum is 27.

Adding to 21251051442 its reverse (24415015212), we get a palindrome (45666066654).

The spelling of 21251051442 in words is "twenty-one billion, two hundred fifty-one million, fifty-one thousand, four hundred forty-two".