1921640 has 32 divisors (see below), whose sum is σ = 4942080. Its totient is φ = 658752.

The previous prime is 1921631. The next prime is 1921657. The reversal of 1921640 is 461291.

It is a happy number.

It is a congruent number.

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, 3152 + ... + 3711.

It is an arithmetic number, because the mean of its divisors is an integer number (154440).

2^1921640 is an apocalyptic number.

1921640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1921640 is an abundant number, since it is smaller than the sum of its proper divisors (3020440).

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

1921640 is a wasteful number, since it uses less digits than its factorization.

1921640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6881 (or 6877 counting only the distinct ones).

The product of its (nonzero) digits is 432, while the sum is 23.

The square root of 1921640 is about 1386.2323037644. The cubic root of 1921640 is about 124.3246780930.

The spelling of 1921640 in words is "one million, nine hundred twenty-one thousand, six hundred forty".