1921405728 has 48 divisors (see below), whose sum is σ = 5502210336. Its totient is φ = 582243840.

The previous prime is 1921405697. The next prime is 1921405729. The reversal of 1921405728 is 8275041291.

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

It is not an unprimeable number, because it can be changed into a prime (1921405729) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 908701 + ... + 910812.

It is an arithmetic number, because the mean of its divisors is an integer number (114629382).

Almost surely, 2^1921405728 is an apocalyptic number.

It is an amenable number.

1921405728 is an abundant number, since it is smaller than the sum of its proper divisors (3580804608).

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

1921405728 is a wasteful number, since it uses less digits than its factorization.

1921405728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1819537 (or 1819529 counting only the distinct ones).

The product of its (nonzero) digits is 40320, while the sum is 39.

The square root of 1921405728 is about 43833.8422682749. The cubic root of 1921405728 is about 1243.1962564217.

The spelling of 1921405728 in words is "one billion, nine hundred twenty-one million, four hundred five thousand, seven hundred twenty-eight".