21209937609601 has 8 divisors (see below), whose sum is σ = 22842152905320. Its totient is φ = 19577819690112.

The previous prime is 21209937609577. The next prime is 21209937609607. The reversal of 21209937609601 is 10690673990212.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 1619257600 + 21208318352001 = 40240^2 + 4605249^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21209937609601 - 2⁵ = 21209937609569 is a prime.

It is a super-2 number, since 2×21209937609601² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21209937609607) 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 in 7 ways as a sum of consecutive naturals, for example, 23891356 + ... + 24763213.

It is an arithmetic number, because the mean of its divisors is an integer number (2855269113165).

Almost surely, 2^{21209937609601} is an apocalyptic number.

It is an amenable number.

21209937609601 is a deficient number, since it is larger than the sum of its proper divisors (1632215295719).

21209937609601 is a wasteful number, since it uses less digits than its factorization.

21209937609601 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 48688115.

The product of its (nonzero) digits is 2204496, while the sum is 55.

The spelling of 21209937609601 in words is "twenty-one trillion, two hundred nine billion, nine hundred thirty-seven million, six hundred nine thousand, six hundred one".