9999651 has 4 divisors (see below), whose sum is σ = 13332872. Its totient is φ = 6666432.

The previous prime is 9999637. The next prime is 9999653. The reversal of 9999651 is 1569999.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1569999 = 3 ⋅523333.

It is not a de Polignac number, because 9999651 - 2¹⁵ = 9966883 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 10.

It is a self number, because there is not a number n which added to its sum of digits gives 9999651.

It is not an unprimeable number, because it can be changed into a prime (9999653) 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, 1666606 + ... + 1666611.

It is an arithmetic number, because the mean of its divisors is an integer number (3333218).

Almost surely, 2^9999651 is an apocalyptic number.

9999651 is a deficient number, since it is larger than the sum of its proper divisors (3333221).

9999651 is a wasteful number, since it uses less digits than its factorization.

9999651 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3333220.

The product of its digits is 196830, while the sum is 48.

The square root of 9999651 is about 3162.2224779417. Note that the first 3 decimals coincide. The cubic root of 9999651 is about 215.4409626483.

The spelling of 9999651 in words is "nine million, nine hundred ninety-nine thousand, six hundred fifty-one".