661129775 has 12 divisors (see below), whose sum is σ = 822727104. Its totient is φ = 527016000.

The previous prime is 661129769. The next prime is 661129783. The reversal of 661129775 is 577921166.

It is not a de Polignac number, because 661129775 - 2¹⁰ = 661128751 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 40031 + ... + 54080.

It is an arithmetic number, because the mean of its divisors is an integer number (68560592).

Almost surely, 2^661129775 is an apocalyptic number.

661129775 is a deficient number, since it is larger than the sum of its proper divisors (161597329).

661129775 is a wasteful number, since it uses less digits than its factorization.

661129775 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 94402 (or 94397 counting only the distinct ones).

The product of its digits is 158760, while the sum is 44.

The square root of 661129775 is about 25712.4439717426. The cubic root of 661129775 is about 871.1552780975.

The spelling of 661129775 in words is "six hundred sixty-one million, one hundred twenty-nine thousand, seven hundred seventy-five".