21431171537 has 2 divisors, whose sum is σ = 21431171538. Its totient is φ = 21431171536.

The previous prime is 21431171507. The next prime is 21431171539. The reversal of 21431171537 is 73517113412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11466340561 + 9964830976 = 107081^2 + 99824^2 .

It is a cyclic number.

It is not a de Polignac number, because 21431171537 - 2⁶ = 21431171473 is a prime.

It is a super-2 number, since 2×21431171537² (a number of 21 digits) contains 22 as substring.

Together with 21431171539, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 21431171497 and 21431171506.

It is not a weakly prime, because it can be changed into another prime (21431171539) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10715585768 + 10715585769.

It is an arithmetic number, because the mean of its divisors is an integer number (10715585769).

Almost surely, 2^21431171537 is an apocalyptic number.

It is an amenable number.

21431171537 is a deficient number, since it is larger than the sum of its proper divisors (1).

21431171537 is an equidigital number, since it uses as much as digits as its factorization.

21431171537 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 17640, while the sum is 35.

Adding to 21431171537 its reverse (73517113412), we get a palindrome (94948284949).

The spelling of 21431171537 in words is "twenty-one billion, four hundred thirty-one million, one hundred seventy-one thousand, five hundred thirty-seven".