21085157537 has 2 divisors, whose sum is σ = 21085157538. Its totient is φ = 21085157536.

The previous prime is 21085157497. The next prime is 21085157567. The reversal of 21085157537 is 73575158012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17172529936 + 3912627601 = 131044^2 + 62551^2 .

It is a cyclic number.

It is not a de Polignac number, because 21085157537 - 2¹⁰ = 21085156513 is a prime.

It is not a weakly prime, because it can be changed into another prime (21085157567) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10542578768 + 10542578769.

It is an arithmetic number, because the mean of its divisors is an integer number (10542578769).

Almost surely, 2^21085157537 is an apocalyptic number.

It is an amenable number.

21085157537 is a deficient number, since it is larger than the sum of its proper divisors (1).

21085157537 is an equidigital number, since it uses as much as digits as its factorization.

21085157537 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 294000, while the sum is 44.

The spelling of 21085157537 in words is "twenty-one billion, eighty-five million, one hundred fifty-seven thousand, five hundred thirty-seven".