21661635050442 has 128 divisors (see below), whose sum is σ = 50092071321600. Its totient is φ = 6931278950400.

The previous prime is 21661635050399. The next prime is 21661635050477. The reversal of 21661635050442 is 24405053616612.

21661635050442 is a `hidden beast` number, since 2 + 1 + 6 + 6 + 1 + 635 + 0 + 5 + 0 + 4 + 4 + 2 = 666.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 102716767 + ... + 102927437.

It is an arithmetic number, because the mean of its divisors is an integer number (391344307200).

Almost surely, 2^{21661635050442} is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21661635050442, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25046035660800).

21661635050442 is an abundant number, since it is smaller than the sum of its proper divisors (28430436271158).

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

21661635050442 is a wasteful number, since it uses less digits than its factorization.

21661635050442 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 211209 (or 211203 counting only the distinct ones).

The product of its (nonzero) digits is 1036800, while the sum is 45.

The spelling of 21661635050442 in words is "twenty-one trillion, six hundred sixty-one billion, six hundred thirty-five million, fifty thousand, four hundred forty-two".