1720660421 has 4 divisors (see below), whose sum is σ = 1720752000. Its totient is φ = 1720568844.

The previous prime is 1720660411. The next prime is 1720660453. The reversal of 1720660421 is 1240660271.

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, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 1720660421 - 2¹⁰ = 1720659397 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1720660411) 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, 6191 + ... + 58988.

It is an arithmetic number, because the mean of its divisors is an integer number (430188000).

Almost surely, 2^1720660421 is an apocalyptic number.

It is an amenable number.

1720660421 is a deficient number, since it is larger than the sum of its proper divisors (91579).

1720660421 is an equidigital number, since it uses as much as digits as its factorization.

1720660421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 91578.

The product of its (nonzero) digits is 4032, while the sum is 29.

The square root of 1720660421 is about 41480.8440246820. The cubic root of 1720660421 is about 1198.2986122528.

The spelling of 1720660421 in words is "one billion, seven hundred twenty million, six hundred sixty thousand, four hundred twenty-one".