1620657 has 6 divisors (see below), whose sum is σ = 2340962. Its totient is φ = 1080432.

The previous prime is 1620631. The next prime is 1620667. The reversal of 1620657 is 7560261.

1620657 is a `hidden beast` number, since 1 + 6 + 2 + 0 + 657 = 666.

It can be written as a sum of positive squares in only one way, i.e., 1115136 + 505521 = 1056^2 + 711^2 .

It is not a de Polignac number, because 1620657 - 2¹⁰ = 1619633 is a prime.

It is a super-2 number, since 2×1620657² = 5253058223298, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1620657.

It is not an unprimeable number, because it can be changed into a prime (1620617) 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 5 ways as a sum of consecutive naturals, for example, 90028 + ... + 90045.

2^1620657 is an apocalyptic number.

It is an amenable number.

1620657 is a deficient number, since it is larger than the sum of its proper divisors (720305).

1620657 is a wasteful number, since it uses less digits than its factorization.

1620657 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 180079 (or 180076 counting only the distinct ones).

The product of its (nonzero) digits is 2520, while the sum is 27.

The square root of 1620657 is about 1273.0502739484. The cubic root of 1620657 is about 117.4619040524.

The spelling of 1620657 in words is "one million, six hundred twenty thousand, six hundred fifty-seven".