21120661515361 has 4 divisors (see below), whose sum is σ = 21146324531392. Its totient is φ = 21094998499332.

The previous prime is 21120661515353. The next prime is 21120661515367. The reversal of 21120661515361 is 16351516602112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21120661515361 - 2³ = 21120661515353 is a prime.

It is a super-3 number, since 3×21120661515361³ (a number of 41 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21120661515367) 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, 12831506781 + ... + 12831508426.

It is an arithmetic number, because the mean of its divisors is an integer number (5286581132848).

Almost surely, 2^{21120661515361} is an apocalyptic number.

It is an amenable number.

21120661515361 is a deficient number, since it is larger than the sum of its proper divisors (25663016031).

21120661515361 is an equidigital number, since it uses as much as digits as its factorization.

21120661515361 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25663016030.

The product of its (nonzero) digits is 64800, while the sum is 40.

The spelling of 21120661515361 in words is "twenty-one trillion, one hundred twenty billion, six hundred sixty-one million, five hundred fifteen thousand, three hundred sixty-one".