21162443561 has 16 divisors (see below), whose sum is σ = 25466544000. Its totient is φ = 17179164288.

The previous prime is 21162443531. The next prime is 21162443563. The reversal of 21162443561 is 16534426112.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21162443561 is a prime.

It is a super-3 number, since 3×21162443561³ (a number of 32 digits) contains 333 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21162443563) 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, 433415 + ... + 479763.

It is an arithmetic number, because the mean of its divisors is an integer number (1591659000).

Almost surely, 2^21162443561 is an apocalyptic number.

It is an amenable number.

21162443561 is a deficient number, since it is larger than the sum of its proper divisors (4304100439).

21162443561 is a wasteful number, since it uses less digits than its factorization.

21162443561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 49808.

The product of its digits is 34560, while the sum is 35.

Adding to 21162443561 its reverse (16534426112), we get a palindrome (37696869673).

The spelling of 21162443561 in words is "twenty-one billion, one hundred sixty-two million, four hundred forty-three thousand, five hundred sixty-one".