1621663 has 6 divisors (see below), whose sum is σ = 1649024. Its totient is φ = 1594656.

The previous prime is 1621657. The next prime is 1621667. The reversal of 1621663 is 3661261.

It is not a de Polignac number, because 1621663 - 2¹³ = 1613471 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1621667) 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, 12706 + ... + 12832.

2^1621663 is an apocalyptic number.

1621663 is a deficient number, since it is larger than the sum of its proper divisors (27361).

1621663 is an equidigital number, since it uses as much as digits as its factorization.

1621663 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 353 (or 240 counting only the distinct ones).

The product of its digits is 1296, while the sum is 25.

The square root of 1621663 is about 1273.4453266631. The cubic root of 1621663 is about 117.4862032993.

The spelling of 1621663 in words is "one million, six hundred twenty-one thousand, six hundred sixty-three".