215401221 has 32 divisors (see below), whose sum is σ = 366291200. Its totient is φ = 122549760.

The previous prime is 215401213. The next prime is 215401223. The reversal of 215401221 is 122104512.

215401221 is a `hidden beast` number, since 2 + 1 + 540 + 122 + 1 = 666.

It is not a de Polignac number, because 215401221 - 2³ = 215401213 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 215401194 and 215401203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (215401223) 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 31 ways as a sum of consecutive naturals, for example, 43185 + ... + 47913.

It is an arithmetic number, because the mean of its divisors is an integer number (11446600).

Almost surely, 2^215401221 is an apocalyptic number.

215401221 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

215401221 is a deficient number, since it is larger than the sum of its proper divisors (150889979).

215401221 is a wasteful number, since it uses less digits than its factorization.

215401221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4986 (or 4980 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 18.

The square root of 215401221 is about 14676.5534441844. The cubic root of 215401221 is about 599.4450618977.

Adding to 215401221 its reverse (122104512), we get a palindrome (337505733).

The spelling of 215401221 in words is "two hundred fifteen million, four hundred one thousand, two hundred twenty-one".