126501991 has 24 divisors (see below), whose sum is σ = 159842592. Its totient is φ = 97996800.

The previous prime is 126501971. The next prime is 126502007. The reversal of 126501991 is 199105621.

It is a happy number.

It is not a de Polignac number, because 126501991 - 2¹³ = 126493799 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (126501901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 197031 + ... + 197671.

It is an arithmetic number, because the mean of its divisors is an integer number (6660108).

Almost surely, 2^126501991 is an apocalyptic number.

126501991 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

126501991 is a deficient number, since it is larger than the sum of its proper divisors (33340601).

126501991 is a wasteful number, since it uses less digits than its factorization.

126501991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 903 (or 892 counting only the distinct ones).

The product of its (nonzero) digits is 4860, while the sum is 34.

The square root of 126501991 is about 11247.3103895998. The cubic root of 126501991 is about 501.9946865360.

It can be divided in two parts, 12650 and 1991, that added together give a palindrome (14641).

The spelling of 126501991 in words is "one hundred twenty-six million, five hundred one thousand, nine hundred ninety-one".