21033115531 has 2 divisors, whose sum is σ = 21033115532. Its totient is φ = 21033115530.

The previous prime is 21033115459. The next prime is 21033115613. The reversal of 21033115531 is 13551133012.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21033115531 - 2¹³ = 21033107339 is a prime.

It is a super-2 number, since 2×21033115531² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21033115496 and 21033115505.

It is not a weakly prime, because it can be changed into another prime (21033110531) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10516557765 + 10516557766.

It is an arithmetic number, because the mean of its divisors is an integer number (10516557766).

Almost surely, 2^21033115531 is an apocalyptic number.

21033115531 is a deficient number, since it is larger than the sum of its proper divisors (1).

21033115531 is an equidigital number, since it uses as much as digits as its factorization.

21033115531 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1350, while the sum is 25.

Adding to 21033115531 its reverse (13551133012), we get a palindrome (34584248543).

The spelling of 21033115531 in words is "twenty-one billion, thirty-three million, one hundred fifteen thousand, five hundred thirty-one".