215161021 has 4 divisors (see below), whose sum is σ = 224515872. Its totient is φ = 205806172.

The previous prime is 215161013. The next prime is 215161069. The reversal of 215161021 is 120161512.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 215161021 - 2³ = 215161013 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 215161021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (215161721) 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, 4677391 + ... + 4677436.

It is an arithmetic number, because the mean of its divisors is an integer number (56128968).

Almost surely, 2^215161021 is an apocalyptic number.

It is an amenable number.

215161021 is a deficient number, since it is larger than the sum of its proper divisors (9354851).

215161021 is an equidigital number, since it uses as much as digits as its factorization.

215161021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9354850.

The product of its (nonzero) digits is 120, while the sum is 19.

The square root of 215161021 is about 14668.3680414694. The cubic root of 215161021 is about 599.2221596356. Note that the first 3 decimals are identical.

The spelling of 215161021 in words is "two hundred fifteen million, one hundred sixty-one thousand, twenty-one".