21049408904 has 8 divisors (see below), whose sum is σ = 39467641710. Its totient is φ = 10524704448.

The previous prime is 21049408901. The next prime is 21049408907. The reversal of 21049408904 is 40980494012.

It is an interprime number because it is at equal distance from previous prime (21049408901) and next prime (21049408907).

It can be written as a sum of positive squares in only one way, i.e., 14185286404 + 6864122500 = 119102^2 + 82850^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is not an unprimeable number, because it can be changed into a prime (21049408901) 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 as a sum of consecutive naturals, namely, 1315588049 + ... + 1315588064.

Almost surely, 2^21049408904 is an apocalyptic number.

It is an amenable number.

21049408904 is a deficient number, since it is larger than the sum of its proper divisors (18418232806).

21049408904 is a wasteful number, since it uses less digits than its factorization.

21049408904 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2631176119 (or 2631176115 counting only the distinct ones).

The product of its (nonzero) digits is 82944, while the sum is 41.

The spelling of 21049408904 in words is "twenty-one billion, forty-nine million, four hundred eight thousand, nine hundred four".