21049042888649 has 4 divisors (see below), whose sum is σ = 21056557722900. Its totient is φ = 21041528054400.

The previous prime is 21049042888613. The next prime is 21049042888661. The reversal of 21049042888649 is 94688824094012.

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 5333526970249 + 15715515918400 = 2309443^2 + 3964280^2 .

It is a cyclic number.

It is not a de Polignac number, because 21049042888649 - 2²⁴ = 21049026111433 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21049042888609) 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, 3757412924 + ... + 3757418525.

It is an arithmetic number, because the mean of its divisors is an integer number (5264139430725).

Almost surely, 2^{21049042888649} is an apocalyptic number.

It is an amenable number.

21049042888649 is a deficient number, since it is larger than the sum of its proper divisors (7514834251).

21049042888649 is an equidigital number, since it uses as much as digits as its factorization.

21049042888649 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7514834250.

The product of its (nonzero) digits is 63700992, while the sum is 65.

The spelling of 21049042888649 in words is "twenty-one trillion, forty-nine billion, forty-two million, eight hundred eighty-eight thousand, six hundred forty-nine".