1620639 has 6 divisors (see below), whose sum is σ = 2340936. Its totient is φ = 1080420.

The previous prime is 1620631. The next prime is 1620667. The reversal of 1620639 is 9360261.

It is a happy number.

1620639 is a `hidden beast` number, since 1 + 6 + 20 + 639 = 666.

It is not a de Polignac number, because 1620639 - 2³ = 1620631 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1620631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 90027 + ... + 90044.

It is an arithmetic number, because the mean of its divisors is an integer number (390156).

2^1620639 is an apocalyptic number.

1620639 is a deficient number, since it is larger than the sum of its proper divisors (720297).

1620639 is a wasteful number, since it uses less digits than its factorization.

1620639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 180077 (or 180074 counting only the distinct ones).

The product of its (nonzero) digits is 1944, while the sum is 27.

The square root of 1620639 is about 1273.0432042943. The cubic root of 1620639 is about 117.4614691831.

The spelling of 1620639 in words is "one million, six hundred twenty thousand, six hundred thirty-nine".