1366521555657 has 16 divisors (see below), whose sum is σ = 1929231015552. Its totient is φ = 857414572800.

The previous prime is 1366521555643. The next prime is 1366521555673. The reversal of 1366521555657 is 7565551256631.

It is not a de Polignac number, because 1366521555657 - 2¹⁵ = 1366521522889 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1366521555597 and 1366521555606.

It is not an unprimeable number, because it can be changed into a prime (1366521555557) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6638323 + ... + 6841079.

It is an arithmetic number, because the mean of its divisors is an integer number (120576938472).

Almost surely, 2^{1366521555657} is an apocalyptic number.

1366521555657 is a gapful number since it is divisible by the number (17) formed by its first and last digit.

It is an amenable number.

1366521555657 is a deficient number, since it is larger than the sum of its proper divisors (562709459895).

1366521555657 is a wasteful number, since it uses less digits than its factorization.

1366521555657 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 334928.

The product of its digits is 28350000, while the sum is 57.

The spelling of 1366521555657 in words is "one trillion, three hundred sixty-six billion, five hundred twenty-one million, five hundred fifty-five thousand, six hundred fifty-seven".