9781551879 has 32 divisors (see below), whose sum is σ = 14625678336. Its totient is φ = 5762689920.

The previous prime is 9781551859. The next prime is 9781551883.

It is a happy number.

9781551879 is nontrivially palindromic in base 10.

It is not a de Polignac number, because 9781551879 - 2⁵ = 9781551847 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9781551859) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1617249 + ... + 1623285.

It is an arithmetic number, because the mean of its divisors is an integer number (457052448).

Almost surely, 2^9781551879 is an apocalyptic number.

9781551879 is a deficient number, since it is larger than the sum of its proper divisors (4844126457).

9781551879 is a wasteful number, since it uses less digits than its factorization.

9781551879 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7415.

The product of its digits is 6350400, while the sum is 60.

The square root of 9781551879 is about 98901.7283923795. The cubic root of 9781551879 is about 2138.6313109526.

The spelling of 9781551879 in words is "nine billion, seven hundred eighty-one million, five hundred fifty-one thousand, eight hundred seventy-nine".