21004042044 has 48 divisors (see below), whose sum is σ = 50467222400. Its totient is φ = 6794093376.

The previous prime is 21004042027. The next prime is 21004042061. The reversal of 21004042044 is 44024040012.

It is an interprime number because it is at equal distance from previous prime (21004042027) and next prime (21004042061).

It is a super-2 number, since 2×21004042044² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21004042044.

It is a congruent number.

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, 105867 + ... + 230685.

Almost surely, 2^21004042044 is an apocalyptic number.

It is an amenable number.

21004042044 is an abundant number, since it is smaller than the sum of its proper divisors (29463180356).

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

21004042044 is a wasteful number, since it uses less digits than its factorization.

21004042044 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 125242 (or 125240 counting only the distinct ones).

The product of its (nonzero) digits is 1024, while the sum is 21.

Adding to 21004042044 its reverse (44024040012), we get a palindrome (65028082056).

The spelling of 21004042044 in words is "twenty-one billion, four million, forty-two thousand, forty-four".