661556151651611 has 32 divisors (see below), whose sum is σ = 700714235289600. Its totient is φ = 622844494398720.

The previous prime is 661556151651607. The next prime is 661556151651631. The reversal of 661556151651611 is 116156151655166.

It is not a de Polignac number, because 661556151651611 - 2² = 661556151651607 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (661556151651631) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 10569477926 + ... + 10569540516.

It is an arithmetic number, because the mean of its divisors is an integer number (21897319852800).

Almost surely, 2^{661556151651611} is an apocalyptic number.

661556151651611 is a deficient number, since it is larger than the sum of its proper divisors (39158083637989).

661556151651611 is a wasteful number, since it uses less digits than its factorization.

661556151651611 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 68099.

The product of its digits is 4860000, while the sum is 56.

The spelling of 661556151651611 in words is "six hundred sixty-one trillion, five hundred fifty-six billion, one hundred fifty-one million, six hundred fifty-one thousand, six hundred eleven".