1799889721 has 4 divisors (see below), whose sum is σ = 2057016832. Its totient is φ = 1542762612.

The previous prime is 1799889691. The next prime is 1799889737. The reversal of 1799889721 is 1279889971.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1799889721 - 2¹⁹ = 1799365433 is a prime.

It is a super-2 number, since 2×1799889721² = 6479206015522915682, which contains 22 as substring.

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 1799889721.

It is not an unprimeable number, because it can be changed into a prime (1799889781) 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, 128563545 + ... + 128563558.

It is an arithmetic number, because the mean of its divisors is an integer number (514254208).

Almost surely, 2^1799889721 is an apocalyptic number.

It is an amenable number.

1799889721 is a deficient number, since it is larger than the sum of its proper divisors (257127111).

1799889721 is an equidigital number, since it uses as much as digits as its factorization.

1799889721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 257127110.

The product of its digits is 4572288, while the sum is 61.

The square root of 1799889721 is about 42425.1072008074. The cubic root of 1799889721 is about 1216.4155564165.

The spelling of 1799889721 in words is "one billion, seven hundred ninety-nine million, eight hundred eighty-nine thousand, seven hundred twenty-one".