561503666 has 4 divisors (see below), whose sum is σ = 842255502. Its totient is φ = 280751832.

The previous prime is 561503647. The next prime is 561503681. The reversal of 561503666 is 666305165.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 489338641 + 72165025 = 22121^2 + 8495^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 140375915 + ... + 140375918.

Almost surely, 2^561503666 is an apocalyptic number.

561503666 is a deficient number, since it is larger than the sum of its proper divisors (280751836).

561503666 is a wasteful number, since it uses less digits than its factorization.

561503666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 280751835.

The product of its (nonzero) digits is 97200, while the sum is 38.

The square root of 561503666 is about 23696.0685768758. The cubic root of 561503666 is about 824.9941430867.

The spelling of 561503666 in words is "five hundred sixty-one million, five hundred three thousand, six hundred sixty-six".