137217991 has 2 divisors, whose sum is σ = 137217992. Its totient is φ = 137217990.

The previous prime is 137217989. The next prime is 137218001. The reversal of 137217991 is 199712731.

It is a weak prime.

It is an emirp because it is prime and its reverse (199712731) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 137217991 - 2¹ = 137217989 is a prime.

Together with 137217989, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (137217961) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 68608995 + 68608996.

It is an arithmetic number, because the mean of its divisors is an integer number (68608996).

Almost surely, 2^137217991 is an apocalyptic number.

137217991 is a deficient number, since it is larger than the sum of its proper divisors (1).

137217991 is an equidigital number, since it uses as much as digits as its factorization.

137217991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 23814, while the sum is 40.

The square root of 137217991 is about 11714.0083233708. The cubic root of 137217991 is about 515.7869528416.

It can be divided in two parts, 13721 and 7991, that added together give a palindrome (21712).

The spelling of 137217991 in words is "one hundred thirty-seven million, two hundred seventeen thousand, nine hundred ninety-one".