21533121037 has 2 divisors, whose sum is σ = 21533121038. Its totient is φ = 21533121036.

The previous prime is 21533121007. The next prime is 21533121121. The reversal of 21533121037 is 73012133512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18554253796 + 2978867241 = 136214^2 + 54579^2 .

It is a cyclic number.

It is not a de Polignac number, because 21533121037 - 2²³ = 21524732429 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21533120996 and 21533121014.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21533121007) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10766560518 + 10766560519.

It is an arithmetic number, because the mean of its divisors is an integer number (10766560519).

Almost surely, 2^21533121037 is an apocalyptic number.

It is an amenable number.

21533121037 is a deficient number, since it is larger than the sum of its proper divisors (1).

21533121037 is an equidigital number, since it uses as much as digits as its factorization.

21533121037 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3780, while the sum is 28.

Adding to 21533121037 its reverse (73012133512), we get a palindrome (94545254549).

The spelling of 21533121037 in words is "twenty-one billion, five hundred thirty-three million, one hundred twenty-one thousand, thirty-seven".