661961047 has 16 divisors (see below), whose sum is σ = 748154880. Its totient is φ = 580165600.

The previous prime is 661961023. The next prime is 661961059. The reversal of 661961047 is 740169166.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-661961047 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661961017) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 312522 + ... + 314632.

It is an arithmetic number, because the mean of its divisors is an integer number (46759680).

Almost surely, 2^661961047 is an apocalyptic number.

661961047 is a deficient number, since it is larger than the sum of its proper divisors (86193833).

661961047 is a wasteful number, since it uses less digits than its factorization.

661961047 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3134.

The product of its (nonzero) digits is 54432, while the sum is 40.

The square root of 661961047 is about 25728.6036737325. The cubic root of 661961047 is about 871.5202410840.

The spelling of 661961047 in words is "six hundred sixty-one million, nine hundred sixty-one thousand, forty-seven".