156561500016661 has 4 divisors (see below), whose sum is σ = 156561628254400. Its totient is φ = 156561371778924.

The previous prime is 156561500016641. The next prime is 156561500016679. The reversal of 156561500016661 is 166610005165651.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 156561500016661 - 2⁷ = 156561500016533 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (156561500016601) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 62269791 + ... + 64735228.

It is an arithmetic number, because the mean of its divisors is an integer number (39140407063600).

Almost surely, 2^{156561500016661} is an apocalyptic number.

It is an amenable number.

156561500016661 is a deficient number, since it is larger than the sum of its proper divisors (128237739).

156561500016661 is a wasteful number, since it uses less digits than its factorization.

156561500016661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 128237738.

The product of its (nonzero) digits is 972000, while the sum is 49.

The spelling of 156561500016661 in words is "one hundred fifty-six trillion, five hundred sixty-one billion, five hundred million, sixteen thousand, six hundred sixty-one".