1954556821 has 4 divisors (see below), whose sum is σ = 2233779232. Its totient is φ = 1675334412.

The previous prime is 1954556777. The next prime is 1954556839. The reversal of 1954556821 is 1286554591.

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 1954556821 - 2¹⁷ = 1954425749 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1954551821) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 139611195 + ... + 139611208.

It is an arithmetic number, because the mean of its divisors is an integer number (558444808).

Almost surely, 2^1954556821 is an apocalyptic number.

It is an amenable number.

1954556821 is a deficient number, since it is larger than the sum of its proper divisors (279222411).

1954556821 is an equidigital number, since it uses as much as digits as its factorization.

1954556821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 279222410.

The product of its digits is 432000, while the sum is 46.

The square root of 1954556821 is about 44210.3700617853. The cubic root of 1954556821 is about 1250.3053805348.

The spelling of 1954556821 in words is "one billion, nine hundred fifty-four million, five hundred fifty-six thousand, eight hundred twenty-one".