21724435137 has 32 divisors (see below), whose sum is σ = 31565721600. Its totient is φ = 13237535808.

The previous prime is 21724435091. The next prime is 21724435169. The reversal of 21724435137 is 73153442712.

It is not a de Polignac number, because 21724435137 - 2⁷ = 21724435009 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21724435095 and 21724435104.

It is not an unprimeable number, because it can be changed into a prime (21724435637) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2586058 + ... + 2594444.

It is an arithmetic number, because the mean of its divisors is an integer number (986428800).

Almost surely, 2^21724435137 is an apocalyptic number.

It is an amenable number.

21724435137 is a deficient number, since it is larger than the sum of its proper divisors (9841286463).

21724435137 is a wasteful number, since it uses less digits than its factorization.

21724435137 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10005.

The product of its digits is 141120, while the sum is 39.

Adding to 21724435137 its reverse (73153442712), we get a palindrome (94877877849).

The spelling of 21724435137 in words is "twenty-one billion, seven hundred twenty-four million, four hundred thirty-five thousand, one hundred thirty-seven".