1642821641 has 4 divisors (see below), whose sum is σ = 1646088192. Its totient is φ = 1639555092.

The previous prime is 1642821629. The next prime is 1642821659. The reversal of 1642821641 is 1461282461.

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 1642821641 - 2⁶ = 1642821577 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1642821671) 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, 1632521 + ... + 1633526.

It is an arithmetic number, because the mean of its divisors is an integer number (411522048).

Almost surely, 2^1642821641 is an apocalyptic number.

It is an amenable number.

1642821641 is a deficient number, since it is larger than the sum of its proper divisors (3266551).

1642821641 is an equidigital number, since it uses as much as digits as its factorization.

1642821641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3266550.

The product of its digits is 18432, while the sum is 35.

The square root of 1642821641 is about 40531.7362199055. The cubic root of 1642821641 is about 1179.9496389979.

The spelling of 1642821641 in words is "one billion, six hundred forty-two million, eight hundred twenty-one thousand, six hundred forty-one".