21644363720042 has 32 divisors (see below), whose sum is σ = 37538428181760. Its totient is φ = 9167798597760.

The previous prime is 21644363720039. The next prime is 21644363720051. The reversal of 21644363720042 is 24002736344612.

It is a junction number, because it is equal to n+sod(n) for n = 21644363719975 and 21644363720002.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1143278 + ... + 6678009.

It is an arithmetic number, because the mean of its divisors is an integer number (1173075880680).

Almost surely, 2^{21644363720042} is an apocalyptic number.

21644363720042 is a deficient number, since it is larger than the sum of its proper divisors (15894064461718).

21644363720042 is a wasteful number, since it uses less digits than its factorization.

21644363720042 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7823606.

The product of its (nonzero) digits is 1161216, while the sum is 44.

The spelling of 21644363720042 in words is "twenty-one trillion, six hundred forty-four billion, three hundred sixty-three million, seven hundred twenty thousand, forty-two".