1620561798 has 12 divisors (see below), whose sum is σ = 3511217268. Its totient is φ = 540187260.

The previous prime is 1620561773. The next prime is 1620561799. The reversal of 1620561798 is 8971650261.

1620561798 is a `hidden beast` number, since 1 + 6 + 20 + 5 + 617 + 9 + 8 = 666.

1620561798 is digitally balanced in base 4, because in such base it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×1620561798² = 5252441082273985608, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1620561799) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 45015588 + ... + 45015623.

It is an arithmetic number, because the mean of its divisors is an integer number (292601439).

Almost surely, 2^1620561798 is an apocalyptic number.

1620561798 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

1620561798 is an abundant number, since it is smaller than the sum of its proper divisors (1890655470).

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

1620561798 is a wasteful number, since it uses less digits than its factorization.

1620561798 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 90031219 (or 90031216 counting only the distinct ones).

The product of its (nonzero) digits is 181440, while the sum is 45.

The square root of 1620561798 is about 40256.2019818065. The cubic root of 1620561798 is about 1174.5960399199.

The spelling of 1620561798 in words is "one billion, six hundred twenty million, five hundred sixty-one thousand, seven hundred ninety-eight".