215106660121 has 4 divisors (see below), whose sum is σ = 218053326772. Its totient is φ = 212159993472.

The previous prime is 215106660061. The next prime is 215106660149. The reversal of 215106660121 is 121066601512.

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 76361584896 + 138745075225 = 276336^2 + 372485^2 .

It is a cyclic number.

It is not a de Polignac number, because 215106660121 - 2¹⁹ = 215106135833 is a prime.

It is a super-2 number, since 2×215106660121² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (215106660161) 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, 1473333216 + ... + 1473333361.

It is an arithmetic number, because the mean of its divisors is an integer number (54513331693).

Almost surely, 2^215106660121 is an apocalyptic number.

It is an amenable number.

215106660121 is a deficient number, since it is larger than the sum of its proper divisors (2946666651).

215106660121 is an equidigital number, since it uses as much as digits as its factorization.

215106660121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2946666650.

The product of its (nonzero) digits is 4320, while the sum is 31.

The spelling of 215106660121 in words is "two hundred fifteen billion, one hundred six million, six hundred sixty thousand, one hundred twenty-one".