7801661 has 4 divisors (see below), whose sum is σ = 8916192. Its totient is φ = 6687132.

The previous prime is 7801649. The next prime is 7801663. The reversal of 7801661 is 1661087.

7801661 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

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, and also an emirpimes, since its reverse is a distinct semiprime: 1661087 = 17 ⋅97711.

It is a cyclic number.

It is not a de Polignac number, because 7801661 - 2⁶ = 7801597 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 (7801663) 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, 557255 + ... + 557268.

It is an arithmetic number, because the mean of its divisors is an integer number (2229048).

Almost surely, 2^7801661 is an apocalyptic number.

It is an amenable number.

7801661 is a deficient number, since it is larger than the sum of its proper divisors (1114531).

7801661 is a wasteful number, since it uses less digits than its factorization.

7801661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1114530.

The product of its (nonzero) digits is 2016, while the sum is 29.

The square root of 7801661 is about 2793.1453596260. The cubic root of 7801661 is about 198.3333245455. Note that the first 4 decimals are identical.

The spelling of 7801661 in words is "seven million, eight hundred one thousand, six hundred sixty-one".