21105215044 has 24 divisors (see below), whose sum is σ = 38239470360. Its totient is φ = 10180257024.

The previous prime is 21105214967. The next prime is 21105215071. The reversal of 21105215044 is 44051250112.

It can be written as a sum of positive squares in 4 ways, for example, as 45400644 + 21059814400 = 6738^2 + 145120^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 65712 + ... + 215704.

It is an arithmetic number, because the mean of its divisors is an integer number (1593311265).

Almost surely, 2^21105215044 is an apocalyptic number.

It is an amenable number.

21105215044 is a deficient number, since it is larger than the sum of its proper divisors (17134255316).

21105215044 is a wasteful number, since it uses less digits than its factorization.

21105215044 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 151239 (or 151237 counting only the distinct ones).

The product of its (nonzero) digits is 1600, while the sum is 25.

Adding to 21105215044 its reverse (44051250112), we get a palindrome (65156465156).

The spelling of 21105215044 in words is "twenty-one billion, one hundred five million, two hundred fifteen thousand, forty-four".