16521233212561 has 32 divisors (see below), whose sum is σ = 21035570192640. Its totient is φ = 12603009408000.

The previous prime is 16521233212499. The next prime is 16521233212607.

16521233212561 is nontrivially palindromic in base 10.

It is not a de Polignac number, because 16521233212561 - 2⁷ = 16521233212433 is a prime.

It is a super-2 number, since 2×16521233212561² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16521213212561) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 11242516 + ... + 12626821.

It is an arithmetic number, because the mean of its divisors is an integer number (657361568520).

Almost surely, 2^{16521233212561} is an apocalyptic number.

16521233212561 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

16521233212561 is a deficient number, since it is larger than the sum of its proper divisors (4514336980079).

16521233212561 is a wasteful number, since it uses less digits than its factorization.

16521233212561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23869545.

The product of its digits is 129600, while the sum is 40.

It can be divided in two parts, 1652123 and 3212561, that added together give a palindrome (4864684).

The spelling of 16521233212561 in words is "sixteen trillion, five hundred twenty-one billion, two hundred thirty-three million, two hundred twelve thousand, five hundred sixty-one".