661729648 has 10 divisors (see below), whose sum is σ = 1282101224. Its totient is φ = 330864816.

The previous prime is 661729637. The next prime is 661729657. The reversal of 661729648 is 846927166.

It is a super-2 number, since 2×661729648² = 875772254084407808, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20679036 + ... + 20679067.

Almost surely, 2^661729648 is an apocalyptic number.

It is an amenable number.

661729648 is a deficient number, since it is larger than the sum of its proper divisors (620371576).

661729648 is a wasteful number, since it uses less digits than its factorization.

661729648 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41358111 (or 41358105 counting only the distinct ones).

The product of its digits is 870912, while the sum is 49.

The square root of 661729648 is about 25724.1063595997. The cubic root of 661729648 is about 871.4186780003.

The spelling of 661729648 in words is "six hundred sixty-one million, seven hundred twenty-nine thousand, six hundred forty-eight".