215440600021 has 4 divisors (see below), whose sum is σ = 220695248844. Its totient is φ = 210185951200.

The previous prime is 215440600013. The next prime is 215440600049. The reversal of 215440600021 is 120006044512.

It is a happy number.

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 111215580100 + 104225019921 = 333490^2 + 322839^2 .

It is a cyclic number.

It is not a de Polignac number, because 215440600021 - 2³ = 215440600013 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (215440601021) 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, 2627324350 + ... + 2627324431.

It is an arithmetic number, because the mean of its divisors is an integer number (55173812211).

Almost surely, 2^215440600021 is an apocalyptic number.

It is an amenable number.

215440600021 is a deficient number, since it is larger than the sum of its proper divisors (5254648823).

215440600021 is an equidigital number, since it uses as much as digits as its factorization.

215440600021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5254648822.

The product of its (nonzero) digits is 1920, while the sum is 25.

Adding to 215440600021 its reverse (120006044512), we get a palindrome (335446644533).

The spelling of 215440600021 in words is "two hundred fifteen billion, four hundred forty million, six hundred thousand, twenty-one".