1721920402 has 4 divisors (see below), whose sum is σ = 2582880606. Its totient is φ = 860960200.

The previous prime is 1721920373. The next prime is 1721920411. The reversal of 1721920402 is 2040291271.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 2040291271 = 167 ⋅12217313.

It can be written as a sum of positive squares in only one way, i.e., 1612905921 + 109014481 = 40161^2 + 10441^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 430480099 + ... + 430480102.

Almost surely, 2^1721920402 is an apocalyptic number.

1721920402 is a deficient number, since it is larger than the sum of its proper divisors (860960204).

1721920402 is an equidigital number, since it uses as much as digits as its factorization.

1721920402 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 860960203.

The product of its (nonzero) digits is 2016, while the sum is 28.

The square root of 1721920402 is about 41496.0287497491. The cubic root of 1721920402 is about 1198.5910319699.

The spelling of 1721920402 in words is "one billion, seven hundred twenty-one million, nine hundred twenty thousand, four hundred two".