21093604649 has 4 divisors (see below), whose sum is σ = 22716189636. Its totient is φ = 19471019664.

The previous prime is 21093604643. The next prime is 21093604663. The reversal of 21093604649 is 94640639012.

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 3185812249 + 17907792400 = 56443^2 + 133820^2 .

It is a cyclic number.

It is not a de Polignac number, because 21093604649 - 2²⁰ = 21092556073 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21093604643) 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, 811292474 + ... + 811292499.

It is an arithmetic number, because the mean of its divisors is an integer number (5679047409).

Almost surely, 2^21093604649 is an apocalyptic number.

It is an amenable number.

21093604649 is a deficient number, since it is larger than the sum of its proper divisors (1622584987).

21093604649 is a wasteful number, since it uses less digits than its factorization.

21093604649 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1622584986.

The product of its (nonzero) digits is 279936, while the sum is 44.

The spelling of 21093604649 in words is "twenty-one billion, ninety-three million, six hundred four thousand, six hundred forty-nine".