21653081398649 has 8 divisors (see below), whose sum is σ = 21660758173320. Its totient is φ = 21645405622656.

The previous prime is 21653081398643. The next prime is 21653081398681. The reversal of 21653081398649 is 94689318035612.

It can be written as a sum of positive squares in 4 ways, for example, as 902323308649 + 20750758090000 = 949907^2 + 4555300^2 .

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 21653081398649 - 2²⁸ = 21652812963193 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21653081398643) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 44536979 + ... + 45020535.

It is an arithmetic number, because the mean of its divisors is an integer number (2707594771665).

Almost surely, 2^{21653081398649} is an apocalyptic number.

It is an amenable number.

21653081398649 is a deficient number, since it is larger than the sum of its proper divisors (7676774671).

21653081398649 is a wasteful number, since it uses less digits than its factorization.

21653081398649 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 499339.

The product of its (nonzero) digits is 67184640, while the sum is 65.

The spelling of 21653081398649 in words is "twenty-one trillion, six hundred fifty-three billion, eighty-one million, three hundred ninety-eight thousand, six hundred forty-nine".