21044442540 has 48 divisors (see below), whose sum is σ = 64281208320. Its totient is φ = 5101682880.

The previous prime is 21044442533. The next prime is 21044442569. The reversal of 21044442540 is 4524444012.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 21044442498 and 21044442507.

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, 15942100 + ... + 15943419.

It is an arithmetic number, because the mean of its divisors is an integer number (1339191840).

Almost surely, 2^21044442540 is an apocalyptic number.

21044442540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21044442540 is an abundant number, since it is smaller than the sum of its proper divisors (43236765780).

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

21044442540 is a wasteful number, since it uses less digits than its factorization.

21044442540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31885542 (or 31885540 counting only the distinct ones).

The product of its (nonzero) digits is 20480, while the sum is 30.

Adding to 21044442540 its reverse (4524444012), we get a palindrome (25568886552).

The spelling of 21044442540 in words is "twenty-one billion, forty-four million, four hundred forty-two thousand, five hundred forty".