21581488273 has 4 divisors (see below), whose sum is σ = 21841506288. Its totient is φ = 21321470260.

The previous prime is 21581488267. The next prime is 21581488297. The reversal of 21581488273 is 37288418512.

It is a happy number.

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 21581488273 - 2⁵ = 21581488241 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21581488073) 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, 130008883 + ... + 130009048.

It is an arithmetic number, because the mean of its divisors is an integer number (5460376572).

Almost surely, 2^21581488273 is an apocalyptic number.

It is an amenable number.

21581488273 is a deficient number, since it is larger than the sum of its proper divisors (260018015).

21581488273 is an equidigital number, since it uses as much as digits as its factorization.

21581488273 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 260018014.

The product of its digits is 860160, while the sum is 49.

The spelling of 21581488273 in words is "twenty-one billion, five hundred eighty-one million, four hundred eighty-eight thousand, two hundred seventy-three".