21111505441 has 4 divisors (see below), whose sum is σ = 22735467412. Its totient is φ = 19487543472.

The previous prime is 21111505439. The next prime is 21111505487. The reversal of 21111505441 is 14450511112.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 3449095441 + 17662410000 = 58729^2 + 132900^2 .

It is a cyclic number.

It is not a de Polignac number, because 21111505441 - 2¹ = 21111505439 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21111505411) 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, 811980966 + ... + 811980991.

It is an arithmetic number, because the mean of its divisors is an integer number (5683866853).

Almost surely, 2^21111505441 is an apocalyptic number.

It is an amenable number.

21111505441 is a deficient number, since it is larger than the sum of its proper divisors (1623961971).

21111505441 is a wasteful number, since it uses less digits than its factorization.

21111505441 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1623961970.

The product of its (nonzero) digits is 800, while the sum is 25.

The spelling of 21111505441 in words is "twenty-one billion, one hundred eleven million, five hundred five thousand, four hundred forty-one".