9915551 has 4 divisors (see below), whose sum is σ = 9945312. Its totient is φ = 9885792.

The previous prime is 9915547. The next prime is 9915559. The reversal of 9915551 is 1555199.

It is a happy number.

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 9915551 - 2² = 9915547 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 (9915559) 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, 14375 + ... + 15048.

It is an arithmetic number, because the mean of its divisors is an integer number (2486328).

Almost surely, 2^9915551 is an apocalyptic number.

9915551 is a deficient number, since it is larger than the sum of its proper divisors (29761).

9915551 is a wasteful number, since it uses less digits than its factorization.

9915551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29760.

The product of its digits is 10125, while the sum is 35.

The square root of 9915551 is about 3148.8967909412. The cubic root of 9915551 is about 214.8352875825.

It can be divided in two parts, 9915 and 551, that multiplied together give a triangular number (5463165 = T₃₃₀₅).

The spelling of 9915551 in words is "nine million, nine hundred fifteen thousand, five hundred fifty-one".