21163523151561 has 16 divisors (see below), whose sum is σ = 32447025859584. Its totient is φ = 12019248904464.

The previous prime is 21163523151451. The next prime is 21163523151619. The reversal of 21163523151561 is 16515132536112.

It is not a de Polignac number, because 21163523151561 - 2¹⁰ = 21163523150537 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21163523151361) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3091367181 + ... + 3091374026.

It is an arithmetic number, because the mean of its divisors is an integer number (2027939116224).

Almost surely, 2^{21163523151561} is an apocalyptic number.

21163523151561 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21163523151561 is a deficient number, since it is larger than the sum of its proper divisors (11283502708023).

21163523151561 is a wasteful number, since it uses less digits than its factorization.

21163523151561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6182741380.

The product of its digits is 162000, while the sum is 42.

Adding to 21163523151561 its reverse (16515132536112), we get a palindrome (37678655687673).

The spelling of 21163523151561 in words is "twenty-one trillion, one hundred sixty-three billion, five hundred twenty-three million, one hundred fifty-one thousand, five hundred sixty-one".