21506013043 has 8 divisors (see below), whose sum is σ = 21921072768. Its totient is φ = 21091297344.

The previous prime is 21506012993. The next prime is 21506013059. The reversal of 21506013043 is 34031060512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21506013043 - 2²¹ = 21503915891 is a prime.

It is a super-2 number, since 2×21506013043² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21506012999 and 21506013017.

It is not an unprimeable number, because it can be changed into a prime (21506014043) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 42046 + ... + 211612.

It is an arithmetic number, because the mean of its divisors is an integer number (2740134096).

Almost surely, 2^21506013043 is an apocalyptic number.

21506013043 is a deficient number, since it is larger than the sum of its proper divisors (415059725).

21506013043 is a wasteful number, since it uses less digits than its factorization.

21506013043 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 172013.

The product of its (nonzero) digits is 2160, while the sum is 25.

Adding to 21506013043 its reverse (34031060512), we get a palindrome (55537073555).

The spelling of 21506013043 in words is "twenty-one billion, five hundred six million, thirteen thousand, forty-three".