21493056868261 has 16 divisors (see below), whose sum is σ = 24255982474560. Its totient is φ = 18864993992320.

The previous prime is 21493056868249. The next prime is 21493056868313. The reversal of 21493056868261 is 16286865039412.

It is a cyclic number.

It is not a de Polignac number, because 21493056868261 - 2²³ = 21493048479653 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21493056868261.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21493056848261) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 15566286 + ... + 16890688.

It is an arithmetic number, because the mean of its divisors is an integer number (1515998904660).

Almost surely, 2^{21493056868261} is an apocalyptic number.

It is an amenable number.

21493056868261 is a deficient number, since it is larger than the sum of its proper divisors (2762925606299).

21493056868261 is a wasteful number, since it uses less digits than its factorization.

21493056868261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1375316.

The product of its (nonzero) digits is 29859840, while the sum is 61.

The spelling of 21493056868261 in words is "twenty-one trillion, four hundred ninety-three billion, fifty-six million, eight hundred sixty-eight thousand, two hundred sixty-one".