1646056821 has 4 divisors (see below), whose sum is σ = 2194742432. Its totient is φ = 1097371212.

The previous prime is 1646056799. The next prime is 1646056823. The reversal of 1646056821 is 1286506461.

It is a happy number.

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 an emirpimes, since its reverse is a distinct semiprime: 1286506461 = 3 ⋅428835487.

It is not a de Polignac number, because 1646056821 - 2⁹ = 1646056309 is a prime.

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 1646056821.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1646056823) 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, 274342801 + ... + 274342806.

It is an arithmetic number, because the mean of its divisors is an integer number (548685608).

Almost surely, 2^1646056821 is an apocalyptic number.

It is an amenable number.

1646056821 is a deficient number, since it is larger than the sum of its proper divisors (548685611).

1646056821 is an equidigital number, since it uses as much as digits as its factorization.

1646056821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 548685610.

The product of its (nonzero) digits is 69120, while the sum is 39.

The square root of 1646056821 is about 40571.6258116433. The cubic root of 1646056821 is about 1180.7236825301.

The spelling of 1646056821 in words is "one billion, six hundred forty-six million, fifty-six thousand, eight hundred twenty-one".