21540040444 has 12 divisors (see below), whose sum is σ = 40594691704. Its totient is φ = 9941557104.

The previous prime is 21540040393. The next prime is 21540040499. The reversal of 21540040444 is 44404004512.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 207115722 + ... + 207115825.

Almost surely, 2^21540040444 is an apocalyptic number.

It is an amenable number.

21540040444 is a deficient number, since it is larger than the sum of its proper divisors (19054651260).

21540040444 is a wasteful number, since it uses less digits than its factorization.

21540040444 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 414231564 (or 414231562 counting only the distinct ones).

The product of its (nonzero) digits is 10240, while the sum is 28.

Adding to 21540040444 its reverse (44404004512), we get a palindrome (65944044956).

The spelling of 21540040444 in words is "twenty-one billion, five hundred forty million, forty thousand, four hundred forty-four".