2215152978921 has 45 divisors (see below), whose sum is σ = 3365433190119. Its totient is φ = 1452023528400.

The previous prime is 2215152978893. The next prime is 2215152978937. The reversal of 2215152978921 is 1298792515122.

The square root of 2215152978921 is 1488339.

It is a perfect power (a square), and thus also a powerful number.

2215152978921 is a `hidden beast` number, since 2 + 2 + 1 + 515 + 29 + 7 + 89 + 21 = 666.

It can be written as a sum of positive squares in only one way, i.e., 72032655321 + 2143120323600 = 268389^2 + 1463940^2 .

It is not a de Polignac number, because 2215152978921 - 2⁵ = 2215152978889 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (2215152978991) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 817096756 + ... + 817099466.

Almost surely, 2^{2215152978921} is an apocalyptic number.

2215152978921 is the 1488339-th square number.

2215152978921 is the 744170-th centered octagonal number.

It is an amenable number.

2215152978921 is a deficient number, since it is larger than the sum of its proper divisors (1150280211198).

2215152978921 is an frugal number, since it uses more digits than its factorization.

2215152978921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5556 (or 2775 counting only the distinct ones).

The product of its digits is 1814400, while the sum is 54.

The spelling of 2215152978921 in words is "two trillion, two hundred fifteen billion, one hundred fifty-two million, nine hundred seventy-eight thousand, nine hundred twenty-one".