1621512220 has 24 divisors (see below), whose sum is σ = 3477628224. Its totient is φ = 634804416.

The previous prime is 1621512203. The next prime is 1621512229. The reversal of 1621512220 is 222151261.

It is a junction number, because it is equal to n+sod(n) for n = 1621512191 and 1621512200.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1621512229) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 861567 + ... + 863446.

It is an arithmetic number, because the mean of its divisors is an integer number (144901176).

Almost surely, 2^1621512220 is an apocalyptic number.

1621512220 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1621512220 is an abundant number, since it is smaller than the sum of its proper divisors (1856116004).

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

1621512220 is a wasteful number, since it uses less digits than its factorization.

1621512220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1725069 (or 1725067 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 22.

The square root of 1621512220 is about 40268.0049170554. The cubic root of 1621512220 is about 1174.8256195117.

Adding to 1621512220 its reverse (222151261), we get a palindrome (1843663481).

The spelling of 1621512220 in words is "one billion, six hundred twenty-one million, five hundred twelve thousand, two hundred twenty".