1620645844 has 12 divisors (see below), whose sum is σ = 2874981844. Its totient is φ = 799222464.

The previous prime is 1620645811. The next prime is 1620645881. The reversal of 1620645844 is 4485460261.

It can be written as a sum of positive squares in 2 ways, for example, as 626000400 + 994645444 = 25020^2 + 31538^2 .

It is a hoax number, since the sum of its digits (40) coincides with the sum of the digits of its distinct prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 1620645797 and 1620645806.

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, 2774787 + ... + 2775370.

Almost surely, 2^1620645844 is an apocalyptic number.

It is an amenable number.

1620645844 is a deficient number, since it is larger than the sum of its proper divisors (1254336000).

1620645844 is a wasteful number, since it uses less digits than its factorization.

1620645844 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5550234 (or 5550232 counting only the distinct ones).

The product of its (nonzero) digits is 184320, while the sum is 40.

The square root of 1620645844 is about 40257.2458571125. The cubic root of 1620645844 is about 1174.6163453046.

The spelling of 1620645844 in words is "one billion, six hundred twenty million, six hundred forty-five thousand, eight hundred forty-four".