10121991 has 8 divisors (see below), whose sum is σ = 14722944. Its totient is φ = 6134520.

The previous prime is 10121963. The next prime is 10121999. The reversal of 10121991 is 19912101.

10121991 is digitally balanced in base 2 and base 4, because in such bases it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 10121991 - 2⁵ = 10121959 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (10121999) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 153331 + ... + 153396.

It is an arithmetic number, because the mean of its divisors is an integer number (1840368).

Almost surely, 2^10121991 is an apocalyptic number.

10121991 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

10121991 is a deficient number, since it is larger than the sum of its proper divisors (4600953).

10121991 is a wasteful number, since it uses less digits than its factorization.

10121991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 306741.

The product of its (nonzero) digits is 162, while the sum is 24.

The square root of 10121991 is about 3181.5076614712. The cubic root of 10121991 is about 216.3160026625.

It can be divided in two parts, 1012 and 1991, that added together give a palindrome (3003).

The spelling of 10121991 in words is "ten million, one hundred twenty-one thousand, nine hundred ninety-one".