21555981242 has 8 divisors (see below), whose sum is σ = 33448936500. Its totient is φ = 10406335744.

The previous prime is 21555981241. The next prime is 21555981263. The reversal of 21555981242 is 24218955512.

It can be written as a sum of positive squares in 2 ways, for example, as 21179271961 + 376709281 = 145531^2 + 19409^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a junction number, because it is equal to n+sod(n) for n = 21555981193 and 21555981202.

It is not an unprimeable number, because it can be changed into a prime (21555981241) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 185827367 + ... + 185827482.

Almost surely, 2^21555981242 is an apocalyptic number.

21555981242 is a deficient number, since it is larger than the sum of its proper divisors (11892955258).

21555981242 is a wasteful number, since it uses less digits than its factorization.

21555981242 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 371654880.

The product of its digits is 288000, while the sum is 44.

The spelling of 21555981242 in words is "twenty-one billion, five hundred fifty-five million, nine hundred eighty-one thousand, two hundred forty-two".