1621215616 has 32 divisors (see below), whose sum is σ = 3277988280. Its totient is φ = 798504960.

The previous prime is 1621215599. The next prime is 1621215671. The reversal of 1621215616 is 6165121261.

It is a tau number, because it is divible by the number of its divisors (32).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 85945 + ... + 103096.

Almost surely, 2^1621215616 is an apocalyptic number.

1621215616 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

1621215616 is an abundant number, since it is smaller than the sum of its proper divisors (1656772664).

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

1621215616 is an equidigital number, since it uses as much as digits as its factorization.

1621215616 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 189122 (or 189110 counting only the distinct ones).

The product of its digits is 4320, while the sum is 31.

The square root of 1621215616 is about 40264.3218743344. The cubic root of 1621215616 is about 1174.7539828378.

Adding to 1621215616 its reverse (6165121261), we get a palindrome (7786336877).

The spelling of 1621215616 in words is "one billion, six hundred twenty-one million, two hundred fifteen thousand, six hundred sixteen".