661015405 has 8 divisors (see below), whose sum is σ = 798543000. Its totient is φ = 525262656.

The previous prime is 661015363. The next prime is 661015427. The reversal of 661015405 is 504510166.

It can be written as a sum of positive squares in 4 ways, for example, as 4169764 + 656845641 = 2042^2 + 25629^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 661015405 - 2¹³ = 661007213 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 442890 + ... + 444379.

It is an arithmetic number, because the mean of its divisors is an integer number (99817875).

Almost surely, 2^661015405 is an apocalyptic number.

It is an amenable number.

661015405 is a deficient number, since it is larger than the sum of its proper divisors (137527595).

661015405 is a wasteful number, since it uses less digits than its factorization.

661015405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 887423.

The product of its (nonzero) digits is 3600, while the sum is 28.

The square root of 661015405 is about 25710.2198551471. The cubic root of 661015405 is about 871.1050409737.

The spelling of 661015405 in words is "six hundred sixty-one million, fifteen thousand, four hundred five".