21948117581 has 8 divisors (see below), whose sum is σ = 24212933304. Its totient is φ = 19765658880.

The previous prime is 21948117559. The next prime is 21948117599. The reversal of 21948117581 is 18571184912.

It can be written as a sum of positive squares in 4 ways, for example, as 2784145225 + 19163972356 = 52765^2 + 138434^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21948117581 - 2²⁶ = 21881008717 is a prime.

It is a super-2 number, since 2×21948117581² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21948117551) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 20588696 + ... + 20589761.

It is an arithmetic number, because the mean of its divisors is an integer number (3026616663).

Almost surely, 2^21948117581 is an apocalyptic number.

It is an amenable number.

21948117581 is a deficient number, since it is larger than the sum of its proper divisors (2264815723).

21948117581 is a wasteful number, since it uses less digits than its factorization.

21948117581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41178511.

The product of its digits is 161280, while the sum is 47.

The spelling of 21948117581 in words is "twenty-one billion, nine hundred forty-eight million, one hundred seventeen thousand, five hundred eighty-one".