1661666650051 has 4 divisors (see below), whose sum is σ = 1672671065104. Its totient is φ = 1650662235000.

The previous prime is 1661666649997. The next prime is 1661666650097. The reversal of 1661666650051 is 1500566661661.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1661666650051 - 2²³ = 1661658261443 is a prime.

It is a super-2 number, since 2×1661666650051² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1661666649977 and 1661666650004.

It is not an unprimeable number, because it can be changed into a prime (1661666654051) 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, 5502207300 + ... + 5502207601.

It is an arithmetic number, because the mean of its divisors is an integer number (418167766276).

Almost surely, 2^{1661666650051} is an apocalyptic number.

1661666650051 is a deficient number, since it is larger than the sum of its proper divisors (11004415053).

1661666650051 is a wasteful number, since it uses less digits than its factorization.

1661666650051 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11004415052.

The product of its (nonzero) digits is 1166400, while the sum is 49.

The spelling of 1661666650051 in words is "one trillion, six hundred sixty-one billion, six hundred sixty-six million, six hundred fifty thousand, fifty-one".