1721866838387 has 4 divisors (see below), whose sum is σ = 1823153123016. Its totient is φ = 1620580553760.

The previous prime is 1721866838383. The next prime is 1721866838389. The reversal of 1721866838387 is 7838386681271.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1721866838387 - 2² = 1721866838383 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1721866838383) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 50643142289 + ... + 50643142322.

It is an arithmetic number, because the mean of its divisors is an integer number (455788280754).

Almost surely, 2^{1721866838387} is an apocalyptic number.

1721866838387 is a gapful number since it is divisible by the number (17) formed by its first and last digit.

1721866838387 is a deficient number, since it is larger than the sum of its proper divisors (101286284629).

1721866838387 is a wasteful number, since it uses less digits than its factorization.

1721866838387 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 101286284628.

The product of its digits is 130056192, while the sum is 68.

The spelling of 1721866838387 in words is "one trillion, seven hundred twenty-one billion, eight hundred sixty-six million, eight hundred thirty-eight thousand, three hundred eighty-seven".