21215452564157 has 2 divisors, whose sum is σ = 21215452564158. Its totient is φ = 21215452564156.

The previous prime is 21215452564093. The next prime is 21215452564193. The reversal of 21215452564157 is 75146525451212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14003080400761 + 7212372163396 = 3742069^2 + 2685586^2 .

It is a cyclic number.

It is not a de Polignac number, because 21215452564157 - 2⁶ = 21215452564093 is a prime.

It is a super-2 number, since 2×21215452564157² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21215452564457) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10607726282078 + 10607726282079.

It is an arithmetic number, because the mean of its divisors is an integer number (10607726282079).

Almost surely, 2^{21215452564157} is an apocalyptic number.

It is an amenable number.

21215452564157 is a deficient number, since it is larger than the sum of its proper divisors (1).

21215452564157 is an equidigital number, since it uses as much as digits as its factorization.

21215452564157 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3360000, while the sum is 50.

The spelling of 21215452564157 in words is "twenty-one trillion, two hundred fifteen billion, four hundred fifty-two million, five hundred sixty-four thousand, one hundred fifty-seven".