127890991 has 2 divisors, whose sum is σ = 127890992. Its totient is φ = 127890990.

The previous prime is 127890979. The next prime is 127891019. The reversal of 127890991 is 199098721.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 127890991 - 2²¹ = 125793839 is a prime.

It is a super-2 number, since 2×127890991² = 32712211157924162, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (127890491) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 63945495 + 63945496.

It is an arithmetic number, because the mean of its divisors is an integer number (63945496).

Almost surely, 2^127890991 is an apocalyptic number.

127890991 is a deficient number, since it is larger than the sum of its proper divisors (1).

127890991 is an equidigital number, since it uses as much as digits as its factorization.

127890991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 81648, while the sum is 46.

The square root of 127890991 is about 11308.8899101548. The cubic root of 127890991 is about 503.8253139780.

It can be divided in two parts, 127890 and 991, that added together give a square (128881 = 359²).

The spelling of 127890991 in words is "one hundred twenty-seven million, eight hundred ninety thousand, nine hundred ninety-one".