1401666697661 has 4 divisors (see below), whose sum is σ = 1401670749024. Its totient is φ = 1401662646300.

The previous prime is 1401666697637. The next prime is 1401666697679. The reversal of 1401666697661 is 1667966661041.

It is a happy number.

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 1401666697661 - 2¹⁴ = 1401666681277 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1401666697661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1401666697261) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1452695 + ... + 2216676.

It is an arithmetic number, because the mean of its divisors is an integer number (350417687256).

Almost surely, 2^{1401666697661} is an apocalyptic number.

It is an amenable number.

1401666697661 is a deficient number, since it is larger than the sum of its proper divisors (4051363).

1401666697661 is an equidigital number, since it uses as much as digits as its factorization.

1401666697661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4051362.

The product of its (nonzero) digits is 11757312, while the sum is 59.

The spelling of 1401666697661 in words is "one trillion, four hundred one billion, six hundred sixty-six million, six hundred ninety-seven thousand, six hundred sixty-one".