7681561 has 4 divisors (see below), whose sum is σ = 7789824. Its totient is φ = 7573300.

The previous prime is 7681543. The next prime is 7681573. The reversal of 7681561 is 1651867.

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 7681561 - 2¹¹ = 7679513 is a prime.

It is a Duffinian number.

7681561 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (7681511) 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, 54025 + ... + 54166.

It is an arithmetic number, because the mean of its divisors is an integer number (1947456).

Almost surely, 2^7681561 is an apocalyptic number.

7681561 is a gapful number since it is divisible by the number (71) formed by its first and last digit.

It is an amenable number.

7681561 is a deficient number, since it is larger than the sum of its proper divisors (108263).

7681561 is a wasteful number, since it uses less digits than its factorization.

7681561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 108262.

The product of its digits is 10080, while the sum is 34.

The square root of 7681561 is about 2771.5629164787. The cubic root of 7681561 is about 197.3103322529.

The spelling of 7681561 in words is "seven million, six hundred eighty-one thousand, five hundred sixty-one".