215145561 has 4 divisors (see below), whose sum is σ = 286860752. Its totient is φ = 143430372.

The previous prime is 215145551. The next prime is 215145571. The reversal of 215145561 is 165541512.

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 an interprime number because it is at equal distance from previous prime (215145551) and next prime (215145571).

It is not a de Polignac number, because 215145561 - 2⁵ = 215145529 is a prime.

It is a super-2 number, since 2×215145561² = 92575224836009442, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (215145521) 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, 35857591 + ... + 35857596.

It is an arithmetic number, because the mean of its divisors is an integer number (71715188).

Almost surely, 2^215145561 is an apocalyptic number.

It is an amenable number.

215145561 is a deficient number, since it is larger than the sum of its proper divisors (71715191).

215145561 is an equidigital number, since it uses as much as digits as its factorization.

215145561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 71715190.

The product of its digits is 6000, while the sum is 30.

The square root of 215145561 is about 14667.8410476798. The cubic root of 215145561 is about 599.2078072893.

The spelling of 215145561 in words is "two hundred fifteen million, one hundred forty-five thousand, five hundred sixty-one".