1621493920 has 48 divisors (see below), whose sum is σ = 3934328328. Its totient is φ = 631065600.

The previous prime is 1621493911. The next prime is 1621493941. The reversal of 1621493920 is 293941261.

It can be written as a sum of positive squares in 4 ways, for example, as 1144333584 + 477160336 = 33828^2 + 21844^2 .

It is a Harshad number since it is a multiple of its sum of digits (37).

It is a self number, because there is not a number n which added to its sum of digits gives 1621493920.

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, 131031 + ... + 142870.

Almost surely, 2^1621493920 is an apocalyptic number.

1621493920 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1621493920 is an abundant number, since it is smaller than the sum of its proper divisors (2312834408).

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

1621493920 is a wasteful number, since it uses less digits than its factorization.

1621493920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 273953 (or 273945 counting only the distinct ones).

The product of its (nonzero) digits is 23328, while the sum is 37.

The square root of 1621493920 is about 40267.7776888668. Note that the first 3 decimals coincide. The cubic root of 1621493920 is about 1174.8211998946.

The spelling of 1621493920 in words is "one billion, six hundred twenty-one million, four hundred ninety-three thousand, nine hundred twenty".