137891521 has 2 divisors, whose sum is σ = 137891522. Its totient is φ = 137891520.

The previous prime is 137891473. The next prime is 137891543. The reversal of 137891521 is 125198731.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 111007296 + 26884225 = 10536^2 + 5185^2 .

It is a cyclic number.

It is not a de Polignac number, because 137891521 - 2¹⁷ = 137760449 is a prime.

It is not a weakly prime, because it can be changed into another prime (137891581) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 68945760 + 68945761.

It is an arithmetic number, because the mean of its divisors is an integer number (68945761).

Almost surely, 2^137891521 is an apocalyptic number.

It is an amenable number.

137891521 is a deficient number, since it is larger than the sum of its proper divisors (1).

137891521 is an equidigital number, since it uses as much as digits as its factorization.

137891521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 15120, while the sum is 37.

The square root of 137891521 is about 11742.7220438874. The cubic root of 137891521 is about 516.6294836000.

The spelling of 137891521 in words is "one hundred thirty-seven million, eight hundred ninety-one thousand, five hundred twenty-one".