661543215 has 36 divisors (see below), whose sum is σ = 1101034584. Its totient is φ = 339169152.

The previous prime is 661543171. The next prime is 661543217. The reversal of 661543215 is 512345166.

It is not a de Polignac number, because 661543215 - 2⁷ = 661543087 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661543217) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 2888721 + ... + 2888949.

It is an arithmetic number, because the mean of its divisors is an integer number (30584294).

Almost surely, 2^661543215 is an apocalyptic number.

661543215 is a deficient number, since it is larger than the sum of its proper divisors (439491369).

661543215 is an equidigital number, since it uses as much as digits as its factorization.

661543215 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 524 (or 266 counting only the distinct ones).

The product of its digits is 21600, while the sum is 33.

The square root of 661543215 is about 25720.4824021635. The cubic root of 661543215 is about 871.3368336709.

The spelling of 661543215 in words is "six hundred sixty-one million, five hundred forty-three thousand, two hundred fifteen".