1687653015409 has 3 divisors (see below), whose sum is σ = 1687654314507. Its totient is φ = 1687651716312.

The previous prime is 1687653015407. The next prime is 1687653015421. The reversal of 1687653015409 is 9045103567861.

The square root of 1687653015409 is 1299097.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in only one way, i.e., 1507136799025 + 180516216384 = 1227655^2 + 424872^2 .

It is not a de Polignac number, because 1687653015409 - 2¹ = 1687653015407 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1687653015409.

It is not an unprimeable number, because it can be changed into a prime (1687653015407) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 649549 + ... + 1948645.

It is an arithmetic number, because the mean of its divisors is an integer number (562551438169).

Almost surely, 2^{1687653015409} is an apocalyptic number.

1687653015409 is the 1299097-th square number.

1687653015409 is the 649549-th centered octagonal number.

It is an amenable number.

1687653015409 is a deficient number, since it is larger than the sum of its proper divisors (1299098).

1687653015409 is an frugal number, since it uses more digits than its factorization.

1687653015409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2598194 (or 1299097 counting only the distinct ones).

The product of its (nonzero) digits is 5443200, while the sum is 55.

The spelling of 1687653015409 in words is "one trillion, six hundred eighty-seven billion, six hundred fifty-three million, fifteen thousand, four hundred nine".