1721889463381 has 18 divisors (see below), whose sum is σ = 1859309128482. Its totient is φ = 1593873313920.

The previous prime is 1721889463367. The next prime is 1721889463391. The reversal of 1721889463381 is 1833649881271.

It can be written as a sum of positive squares in 3 ways, for example, as 244184222500 + 1477705240881 = 494150^2 + 1215609^2 .

It is not a de Polignac number, because 1721889463381 - 2¹³ = 1721889455189 is a prime.

It is a super-2 number, since 2×1721889463381² (a number of 25 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (61).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1721889463391) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 174222466 + ... + 174232348.

Almost surely, 2^{1721889463381} is an apocalyptic number.

It is an amenable number.

1721889463381 is a deficient number, since it is larger than the sum of its proper divisors (137419665101).

1721889463381 is an frugal number, since it uses more digits than its factorization.

1721889463381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19861 (or 9961 counting only the distinct ones).

The product of its digits is 13934592, while the sum is 61.

Multiplying 1721889463381 by its sum of digits (61), we get a square (105035257266241 = 10248671²).

1721889463381 divided by its sum of digits (61) gives a square (28227696121 = 168011²).

The spelling of 1721889463381 in words is "one trillion, seven hundred twenty-one billion, eight hundred eighty-nine million, four hundred sixty-three thousand, three hundred eighty-one".