21871518441 has 4 divisors (see below), whose sum is σ = 29162024592. Its totient is φ = 14581012292.

The previous prime is 21871518437. The next prime is 21871518451. The reversal of 21871518441 is 14481517812.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21871518441 - 2² = 21871518437 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21871518393 and 21871518402.

It is not an unprimeable number, because it can be changed into a prime (21871518401) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3645253071 + ... + 3645253076.

It is an arithmetic number, because the mean of its divisors is an integer number (7290506148).

Almost surely, 2^21871518441 is an apocalyptic number.

It is an amenable number.

21871518441 is a deficient number, since it is larger than the sum of its proper divisors (7290506151).

21871518441 is an equidigital number, since it uses as much as digits as its factorization.

21871518441 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7290506150.

The product of its digits is 71680, while the sum is 42.

The spelling of 21871518441 in words is "twenty-one billion, eight hundred seventy-one million, five hundred eighteen thousand, four hundred forty-one".