1721287867 has 4 divisors (see below), whose sum is σ = 1853694640. Its totient is φ = 1588881096.

The previous prime is 1721287847. The next prime is 1721287873. The reversal of 1721287867 is 7687821271.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 7687821271 = 13 ⋅591370867.

It is a cyclic number.

It is not a de Polignac number, because 1721287867 - 2¹⁵ = 1721255099 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 1721287867.

It is not an unprimeable number, because it can be changed into a prime (1721287817) 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, 66203367 + ... + 66203392.

It is an arithmetic number, because the mean of its divisors is an integer number (463423660).

Almost surely, 2^1721287867 is an apocalyptic number.

1721287867 is a deficient number, since it is larger than the sum of its proper divisors (132406773).

1721287867 is a wasteful number, since it uses less digits than its factorization.

1721287867 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 132406772.

The product of its digits is 526848, while the sum is 49.

The square root of 1721287867 is about 41488.4064167329. The cubic root of 1721287867 is about 1198.4442494143. Note that the first 3 decimals are identical.

The spelling of 1721287867 in words is "one billion, seven hundred twenty-one million, two hundred eighty-seven thousand, eight hundred sixty-seven".