21221423440644 has 24 divisors (see below), whose sum is σ = 56590462508608. Its totient is φ = 6063263840160.

The previous prime is 21221423440619. The next prime is 21221423440661. The reversal of 21221423440644 is 44604432412212.

It is a super-2 number, since 2×21221423440644² (a number of 27 digits) contains 22 as substring.

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, 126317996587 + ... + 126317996754.

Almost surely, 2^{21221423440644} is an apocalyptic number.

It is an amenable number.

21221423440644 is an abundant number, since it is smaller than the sum of its proper divisors (35369039067964).

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

21221423440644 is a wasteful number, since it uses less digits than its factorization.

21221423440644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 252635993355 (or 252635993353 counting only the distinct ones).

The product of its (nonzero) digits is 294912, while the sum is 39.

Adding to 21221423440644 its reverse (44604432412212), we get a palindrome (65825855852856).

The spelling of 21221423440644 in words is "twenty-one trillion, two hundred twenty-one billion, four hundred twenty-three million, four hundred forty thousand, six hundred forty-four".