661043601 has 24 divisors (see below), whose sum is σ = 981373536. Its totient is φ = 428541120.

The previous prime is 661043557. The next prime is 661043609. The reversal of 661043601 is 106340166.

661043601 is a `hidden beast` number, since 6 + 6 + 10 + 43 + 601 = 666.

It is not a de Polignac number, because 661043601 - 2¹¹ = 661041553 is a prime.

It is not an unprimeable number, because it can be changed into a prime (661043609) 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, 86506 + ... + 93836.

It is an arithmetic number, because the mean of its divisors is an integer number (40890564).

Almost surely, 2^661043601 is an apocalyptic number.

It is an amenable number.

661043601 is a deficient number, since it is larger than the sum of its proper divisors (320329935).

661043601 is a wasteful number, since it uses less digits than its factorization.

661043601 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7613 (or 7610 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 27.

The square root of 661043601 is about 25710.7681915574. The cubic root of 661043601 is about 871.1174266299.

Adding to 661043601 its reverse (106340166), we get a palindrome (767383767).

The spelling of 661043601 in words is "six hundred sixty-one million, forty-three thousand, six hundred one".