215711961 has 24 divisors (see below), whose sum is σ = 301480704. Its totient is φ = 137142720.

The previous prime is 215711953. The next prime is 215712001. The reversal of 215711961 is 169117512.

215711961 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 215711961 - 2³ = 215711953 is a prime.

It is not an unprimeable number, because it can be changed into a prime (215711911) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 217176 + ... + 218166.

It is an arithmetic number, because the mean of its divisors is an integer number (12561696).

Almost surely, 2^215711961 is an apocalyptic number.

It is an amenable number.

215711961 is a deficient number, since it is larger than the sum of its proper divisors (85768743).

215711961 is an equidigital number, since it uses as much as digits as its factorization.

215711961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1121 (or 1084 counting only the distinct ones).

The product of its digits is 3780, while the sum is 33.

The square root of 215711961 is about 14687.1359018700. The cubic root of 215711961 is about 599.7331785837.

It can be divided in two parts, 21571 and 1961, that added together give a palindrome (23532).

The spelling of 215711961 in words is "two hundred fifteen million, seven hundred eleven thousand, nine hundred sixty-one".