21615220043 has 4 divisors (see below), whose sum is σ = 21684278568. Its totient is φ = 21546161520.

The previous prime is 21615220037. The next prime is 21615220057. The reversal of 21615220043 is 34002251612.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21615220043 - 2³⁴ = 4435350859 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21615219994 and 21615220021.

It is not an unprimeable number, because it can be changed into a prime (21615220243) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 34528793 + ... + 34529418.

It is an arithmetic number, because the mean of its divisors is an integer number (5421069642).

Almost surely, 2^21615220043 is an apocalyptic number.

21615220043 is a deficient number, since it is larger than the sum of its proper divisors (69058525).

21615220043 is an equidigital number, since it uses as much as digits as its factorization.

21615220043 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 69058524.

The product of its (nonzero) digits is 2880, while the sum is 26.

Adding to 21615220043 its reverse (34002251612), we get a palindrome (55617471655).

The spelling of 21615220043 in words is "twenty-one billion, six hundred fifteen million, two hundred twenty thousand, forty-three".