21530013157 has 2 divisors, whose sum is σ = 21530013158. Its totient is φ = 21530013156.

The previous prime is 21530013149. The next prime is 21530013173. The reversal of 21530013157 is 75131003512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15229781281 + 6300231876 = 123409^2 + 79374^2 .

It is a cyclic number.

It is not a de Polignac number, because 21530013157 - 2³ = 21530013149 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21530013187) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10765006578 + 10765006579.

It is an arithmetic number, because the mean of its divisors is an integer number (10765006579).

Almost surely, 2^21530013157 is an apocalyptic number.

It is an amenable number.

21530013157 is a deficient number, since it is larger than the sum of its proper divisors (1).

21530013157 is an equidigital number, since it uses as much as digits as its factorization.

21530013157 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3150, while the sum is 28.

Adding to 21530013157 its reverse (75131003512), we get a palindrome (96661016669).

The spelling of 21530013157 in words is "twenty-one billion, five hundred thirty million, thirteen thousand, one hundred fifty-seven".