137897521 has 2 divisors, whose sum is σ = 137897522. Its totient is φ = 137897520.

The previous prime is 137897519. The next prime is 137897527. The reversal of 137897521 is 125798731.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 110019121 + 27878400 = 10489^2 + 5280^2 .

It is a cyclic number.

It is not a de Polignac number, because 137897521 - 2¹ = 137897519 is a prime.

Together with 137897519, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (137897527) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 68948760 + 68948761.

It is an arithmetic number, because the mean of its divisors is an integer number (68948761).

Almost surely, 2^137897521 is an apocalyptic number.

It is an amenable number.

137897521 is a deficient number, since it is larger than the sum of its proper divisors (1).

137897521 is an equidigital number, since it uses as much as digits as its factorization.

137897521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 105840, while the sum is 43.

The square root of 137897521 is about 11742.9775185002. The cubic root of 137897521 is about 516.6369767654.

The spelling of 137897521 in words is "one hundred thirty-seven million, eight hundred ninety-seven thousand, five hundred twenty-one".