21215452564121 has 4 divisors (see below), whose sum is σ = 21215478181044. Its totient is φ = 21215426947200.

The previous prime is 21215452564093. The next prime is 21215452564157. The reversal of 21215452564121 is 12146525451212.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 2249985000025 + 18965467564096 = 1499995^2 + 4354936^2 .

It is a cyclic number.

It is not a de Polignac number, because 21215452564121 - 2³⁰ = 21214378822297 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21215452564021) 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, 11523200 + ... + 13236881.

It is an arithmetic number, because the mean of its divisors is an integer number (5303869545261).

Almost surely, 2^{21215452564121} is an apocalyptic number.

It is an amenable number.

21215452564121 is a deficient number, since it is larger than the sum of its proper divisors (25616923).

21215452564121 is an equidigital number, since it uses as much as digits as its factorization.

21215452564121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25616922.

The product of its digits is 192000, while the sum is 41.

The spelling of 21215452564121 in words is "twenty-one trillion, two hundred fifteen billion, four hundred fifty-two million, five hundred sixty-four thousand, one hundred twenty-one".