21855665442 has 16 divisors (see below), whose sum is σ = 47073741120. Its totient is φ = 6724820112.

The previous prime is 21855665437. The next prime is 21855665453. The reversal of 21855665442 is 24456655812.

It is a super-2 number, since 2×21855665442² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21855665391 and 21855665400.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 140100342 + ... + 140100497.

It is an arithmetic number, because the mean of its divisors is an integer number (2942108820).

Almost surely, 2^21855665442 is an apocalyptic number.

21855665442 is an abundant number, since it is smaller than the sum of its proper divisors (25218075678).

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

21855665442 is a wasteful number, since it uses less digits than its factorization.

21855665442 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 280200857.

The product of its digits is 2304000, while the sum is 48.

The spelling of 21855665442 in words is "twenty-one billion, eight hundred fifty-five million, six hundred sixty-five thousand, four hundred forty-two".