21520404043 has 16 divisors (see below), whose sum is σ = 22545446400. Its totient is φ = 20502979200.

The previous prime is 21520404041. The next prime is 21520404053. The reversal of 21520404043 is 34040402512.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21520404043 - 2¹ = 21520404041 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21520403999 and 21520404017.

It is not an unprimeable number, because it can be changed into a prime (21520404041) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8474668 + ... + 8477206.

It is an arithmetic number, because the mean of its divisors is an integer number (1409090400).

Almost surely, 2^21520404043 is an apocalyptic number.

21520404043 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

21520404043 is a deficient number, since it is larger than the sum of its proper divisors (1025042357).

21520404043 is a wasteful number, since it uses less digits than its factorization.

21520404043 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3882.

The product of its (nonzero) digits is 3840, while the sum is 25.

Adding to 21520404043 its reverse (34040402512), we get a palindrome (55560806555).

The spelling of 21520404043 in words is "twenty-one billion, five hundred twenty million, four hundred four thousand, forty-three".