21155144022644 has 24 divisors (see below), whose sum is σ = 37410503656680. Its totient is φ = 10466685081216.

The previous prime is 21155144022643. The next prime is 21155144022647. The reversal of 21155144022644 is 44622044155112.

It can be written as a sum of positive squares in 4 ways, for example, as 13871244745744 + 7283899276900 = 3724412^2 + 2698870^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21155144022643) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 31718147 + ... + 32378250.

It is an arithmetic number, because the mean of its divisors is an integer number (1558770985695).

Almost surely, 2^{21155144022644} is an apocalyptic number.

It is an amenable number.

21155144022644 is a deficient number, since it is larger than the sum of its proper divisors (16255359634036).

21155144022644 is a wasteful number, since it uses less digits than its factorization.

21155144022644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 64097267 (or 64097265 counting only the distinct ones).

The product of its (nonzero) digits is 307200, while the sum is 41.

Adding to 21155144022644 its reverse (44622044155112), we get a palindrome (65777188177756).

The spelling of 21155144022644 in words is "twenty-one trillion, one hundred fifty-five billion, one hundred forty-four million, twenty-two thousand, six hundred forty-four".