1621555560 has 48 divisors (see below), whose sum is σ = 5270056740. Its totient is φ = 432414720.

The previous prime is 1621555553. The next prime is 1621555571. The reversal of 1621555560 is 655551261.

It can be written as a sum of positive squares in 2 ways, for example, as 1347917796 + 273637764 = 36714^2 + 16542^2 .

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2251801 + ... + 2252520.

Almost surely, 2^1621555560 is an apocalyptic number.

1621555560 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1621555560 is an abundant number, since it is smaller than the sum of its proper divisors (3648501180).

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

1621555560 is a wasteful number, since it uses less digits than its factorization.

1621555560 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4504338 (or 4504331 counting only the distinct ones).

The product of its (nonzero) digits is 45000, while the sum is 36.

The square root of 1621555560 is about 40268.5430578262. The cubic root of 1621555560 is about 1174.8360863850.

The spelling of 1621555560 in words is "one billion, six hundred twenty-one million, five hundred fifty-five thousand, five hundred sixty".