661512201 has 16 divisors (see below), whose sum is σ = 1028592000. Its totient is φ = 378006384.

The previous prime is 661512197. The next prime is 661512209. The reversal of 661512201 is 102215166.

It is not a de Polignac number, because 661512201 - 2² = 661512197 is a prime.

It is not an unprimeable number, because it can be changed into a prime (661512209) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 320406 + ... + 322463.

It is an arithmetic number, because the mean of its divisors is an integer number (64287000).

Almost surely, 2^661512201 is an apocalyptic number.

It is an amenable number.

661512201 is a deficient number, since it is larger than the sum of its proper divisors (367079799).

661512201 is an equidigital number, since it uses as much as digits as its factorization.

661512201 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 642893 (or 642879 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 24.

The square root of 661512201 is about 25719.8794903864. The cubic root of 661512201 is about 871.3232169929.

Adding to 661512201 its reverse (102215166), we get a palindrome (763727367).

The spelling of 661512201 in words is "six hundred sixty-one million, five hundred twelve thousand, two hundred one".