21154535620561 has 8 divisors (see below), whose sum is σ = 24176662850880. Its totient is φ = 18132421068528.

The previous prime is 21154535620481. The next prime is 21154535620597. The reversal of 21154535620561 is 16502653545112.

It is a happy number.

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 21154535620561 - 2¹⁵ = 21154535587793 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21154535660561) 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, 724950 + ... + 6544816.

It is an arithmetic number, because the mean of its divisors is an integer number (3022082856360).

Almost surely, 2^{21154535620561} is an apocalyptic number.

It is an amenable number.

21154535620561 is a deficient number, since it is larger than the sum of its proper divisors (3022127230319).

21154535620561 is an equidigital number, since it uses as much as digits as its factorization.

21154535620561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6339143.

The product of its (nonzero) digits is 1080000, while the sum is 46.

The spelling of 21154535620561 in words is "twenty-one trillion, one hundred fifty-four billion, five hundred thirty-five million, six hundred twenty thousand, five hundred sixty-one".