215213121 has 6 divisors (see below), whose sum is σ = 310863410. Its totient is φ = 143475408.

The previous prime is 215213099. The next prime is 215213137. The reversal of 215213121 is 121312512.

215213121 is a `hidden beast` number, since 21 + 521 + 3 + 121 = 666.

It can be written as a sum of positive squares in only one way, i.e., 150185025 + 65028096 = 12255^2 + 8064^2 .

It is not a de Polignac number, because 215213121 - 2¹⁵ = 215180353 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 215213094 and 215213103.

It is not an unprimeable number, because it can be changed into a prime (215213161) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 11956276 + ... + 11956293.

Almost surely, 2^215213121 is an apocalyptic number.

It is an amenable number.

215213121 is a deficient number, since it is larger than the sum of its proper divisors (95650289).

215213121 is a wasteful number, since it uses less digits than its factorization.

215213121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23912575 (or 23912572 counting only the distinct ones).

The product of its digits is 120, while the sum is 18.

The square root of 215213121 is about 14670.1438643253. The cubic root of 215213121 is about 599.2705217953.

Adding to 215213121 its reverse (121312512), we get a palindrome (336525633).

It can be divided in two parts, 21521 and 3121, that added together give a palindrome (24642).

The spelling of 215213121 in words is "two hundred fifteen million, two hundred thirteen thousand, one hundred twenty-one".