1620631 has 2 divisors, whose sum is σ = 1620632. Its totient is φ = 1620630.

The previous prime is 1620629. The next prime is 1620667. The reversal of 1620631 is 1360261.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1620631 - 2¹ = 1620629 is a prime.

It is a super-2 number, since 2×1620631² = 5252889676322, which contains 22 as substring.

Together with 1620629, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 1620599 and 1620608.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1620611) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 810315 + 810316.

It is an arithmetic number, because the mean of its divisors is an integer number (810316).

2^1620631 is an apocalyptic number.

1620631 is a deficient number, since it is larger than the sum of its proper divisors (1).

1620631 is an equidigital number, since it uses as much as digits as its factorization.

1620631 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 216, while the sum is 19.

The square root of 1620631 is about 1273.0400622133. The cubic root of 1620631 is about 117.4612759068.

Adding to 1620631 its reverse (1360261), we get a palindrome (2980892).

The spelling of 1620631 in words is "one million, six hundred twenty thousand, six hundred thirty-one".