1621543440 has 320 divisors, whose sum is σ = 5723633664. Its totient is φ = 376320000.

The previous prime is 1621543411. The next prime is 1621543477. The reversal of 1621543440 is 443451261.

1621543440 = T₁₇₁₆₅ + T₁₇₁₆₆ + ... + T₁₇₁₇₅.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 1621543398 and 1621543407.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 7684935 + ... + 7685145.

Almost surely, 2^1621543440 is an apocalyptic number.

1621543440 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1621543440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2861816832).

1621543440 is an abundant number, since it is smaller than the sum of its proper divisors (4102090224).

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

1621543440 is a wasteful number, since it uses less digits than its factorization.

1621543440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 350 (or 344 counting only the distinct ones).

The product of its (nonzero) digits is 11520, while the sum is 30.

The square root of 1621543440 is about 40268.3925678689. The cubic root of 1621543440 is about 1174.8331593502.

The spelling of 1621543440 in words is "one billion, six hundred twenty-one million, five hundred forty-three thousand, four hundred forty".