9991051 has 24 divisors (see below), whose sum is σ = 12312000. Its totient is φ = 8072064.

The previous prime is 9991027. The next prime is 9991057. The reversal of 9991051 is 1501999.

9991051 is digitally balanced in base 2 and base 3, because in such bases it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 9991051 - 2¹⁵ = 9958283 is a prime.

It is a super-2 number, since 2×9991051² = 199642200169202, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 9990998 and 9991016.

It is not an unprimeable number, because it can be changed into a prime (9991057) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 112215 + ... + 112303.

It is an arithmetic number, because the mean of its divisors is an integer number (513000).

Almost surely, 2^9991051 is an apocalyptic number.

9991051 is the 2581-st pentagonal number.

9991051 is a deficient number, since it is larger than the sum of its proper divisors (2320949).

9991051 is a wasteful number, since it uses less digits than its factorization.

9991051 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 211 (or 204 counting only the distinct ones).

The product of its (nonzero) digits is 3645, while the sum is 34.

The square root of 9991051 is about 3160.8623823254. The cubic root of 9991051 is about 215.3791830361.

The spelling of 9991051 in words is "nine million, nine hundred ninety-one thousand, fifty-one".