1921261728 has 48 divisors (see below), whose sum is σ = 5064474240. Its totient is φ = 637733376.

The previous prime is 1921261717. The next prime is 1921261733. The reversal of 1921261728 is 8271621291.

It is a tau number, because it is divible by the number of its divisors (48).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18925 + ... + 64812.

It is an arithmetic number, because the mean of its divisors is an integer number (105509880).

Almost surely, 2^1921261728 is an apocalyptic number.

It is an amenable number.

1921261728 is an abundant number, since it is smaller than the sum of its proper divisors (3143212512).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1921261728 is a wasteful number, since it uses less digits than its factorization.

1921261728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 83989 (or 83981 counting only the distinct ones).

The product of its digits is 24192, while the sum is 39.

The square root of 1921261728 is about 43832.1996710181. The cubic root of 1921261728 is about 1243.1651984779.

The spelling of 1921261728 in words is "one billion, nine hundred twenty-one million, two hundred sixty-one thousand, seven hundred twenty-eight".