137715821 has 2 divisors, whose sum is σ = 137715822. Its totient is φ = 137715820.

The previous prime is 137715817. The next prime is 137715833. The reversal of 137715821 is 128517731.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 99102025 + 38613796 = 9955^2 + 6214^2 .

It is an emirp because it is prime and its reverse (128517731) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 137715821 - 2² = 137715817 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (137714821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 68857910 + 68857911.

It is an arithmetic number, because the mean of its divisors is an integer number (68857911).

Almost surely, 2^137715821 is an apocalyptic number.

It is an amenable number.

137715821 is a deficient number, since it is larger than the sum of its proper divisors (1).

137715821 is an equidigital number, since it uses as much as digits as its factorization.

137715821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 11760, while the sum is 35.

The square root of 137715821 is about 11735.2384296187. The cubic root of 137715821 is about 516.4099622921.

The spelling of 137715821 in words is "one hundred thirty-seven million, seven hundred fifteen thousand, eight hundred twenty-one".