661040642 has 8 divisors (see below), whose sum is σ = 991831932. Its totient is φ = 330430000.

The previous prime is 661040599. The next prime is 661040659. The reversal of 661040642 is 246040166.

It can be written as a sum of positive squares in 2 ways, for example, as 533101921 + 127938721 = 23089^2 + 11311^2 .

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

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 35609 + ... + 50892.

Almost surely, 2^661040642 is an apocalyptic number.

661040642 is a deficient number, since it is larger than the sum of its proper divisors (330791290).

661040642 is a wasteful number, since it uses less digits than its factorization.

661040642 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 90324.

The product of its (nonzero) digits is 6912, while the sum is 29.

The square root of 661040642 is about 25710.7106475103. The cubic root of 661040642 is about 871.1161268465.

The spelling of 661040642 in words is "six hundred sixty-one million, forty thousand, six hundred forty-two".