1661151565623 has 8 divisors (see below), whose sum is σ = 2416220459136. Its totient is φ = 1006758524600.

The previous prime is 1661151565607. The next prime is 1661151565631. The reversal of 1661151565623 is 3265651511661.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1661151565623 - 2⁴ = 1661151565607 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661151565523) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 25168963083 + ... + 25168963148.

It is an arithmetic number, because the mean of its divisors is an integer number (302027557392).

Almost surely, 2^{1661151565623} is an apocalyptic number.

1661151565623 is a deficient number, since it is larger than the sum of its proper divisors (755068893513).

1661151565623 is a wasteful number, since it uses less digits than its factorization.

1661151565623 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50337926245.

The product of its digits is 972000, while the sum is 48.

The spelling of 1661151565623 in words is "one trillion, six hundred sixty-one billion, one hundred fifty-one million, five hundred sixty-five thousand, six hundred twenty-three".