21611457281 has 12 divisors (see below), whose sum is σ = 23077754880. Its totient is φ = 20233650240.

The previous prime is 21611457269. The next prime is 21611457311. The reversal of 21611457281 is 18275411612.

It is not a de Polignac number, because 21611457281 - 2²² = 21607262977 is a prime.

It is a super-2 number, since 2×21611457281² (a number of 21 digits) contains 22 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 (21611457251) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 140561 + ... + 250958.

It is an arithmetic number, because the mean of its divisors is an integer number (1923146240).

Almost surely, 2^21611457281 is an apocalyptic number.

It is an amenable number.

21611457281 is a deficient number, since it is larger than the sum of its proper divisors (1466297599).

21611457281 is a wasteful number, since it uses less digits than its factorization.

21611457281 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 391744 (or 391727 counting only the distinct ones).

The product of its digits is 26880, while the sum is 38.

Adding to 21611457281 its reverse (18275411612), we get a palindrome (39886868893).

The spelling of 21611457281 in words is "twenty-one billion, six hundred eleven million, four hundred fifty-seven thousand, two hundred eighty-one".