137681221 has 2 divisors, whose sum is σ = 137681222. Its totient is φ = 137681220.

The previous prime is 137681191. The next prime is 137681263. The reversal of 137681221 is 122186731.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 100300225 + 37380996 = 10015^2 + 6114^2 .

It is an emirp because it is prime and its reverse (122186731) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 137681221 - 2⁹ = 137680709 is a prime.

It is a super-2 number, since 2×137681221² = 37912237232101682, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (137681021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 68840610 + 68840611.

It is an arithmetic number, because the mean of its divisors is an integer number (68840611).

Almost surely, 2^137681221 is an apocalyptic number.

It is an amenable number.

137681221 is a deficient number, since it is larger than the sum of its proper divisors (1).

137681221 is an equidigital number, since it uses as much as digits as its factorization.

137681221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4032, while the sum is 31.

The square root of 137681221 is about 11733.7641445531. The cubic root of 137681221 is about 516.3667107103.

The spelling of 137681221 in words is "one hundred thirty-seven million, six hundred eighty-one thousand, two hundred twenty-one".