21531553442 has 12 divisors (see below), whose sum is σ = 37570363830. Its totient is φ = 9227808576.

The previous prime is 21531553427. The next prime is 21531553453. The reversal of 21531553442 is 24435513512.

It can be written as a sum of positive squares in only one way, i.e., 15104164201 + 6427389241 = 122899^2 + 80171^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 109854767 + ... + 109854962.

Almost surely, 2^21531553442 is an apocalyptic number.

21531553442 is a deficient number, since it is larger than the sum of its proper divisors (16038810388).

21531553442 is a wasteful number, since it uses less digits than its factorization.

21531553442 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 219709745 (or 219709738 counting only the distinct ones).

The product of its digits is 72000, while the sum is 35.

The spelling of 21531553442 in words is "twenty-one billion, five hundred thirty-one million, five hundred fifty-three thousand, four hundred forty-two".