1631621 has 4 divisors (see below), whose sum is σ = 1646700. Its totient is φ = 1616544.

The previous prime is 1631611. The next prime is 1631629. The reversal of 1631621 is 1261361.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1261361 = 59 ⋅21379.

It can be written as a sum of positive squares in 2 ways, for example, as 390625 + 1240996 = 625^2 + 1114^2 .

It is a cyclic number.

It is not a de Polignac number, because 1631621 - 2⁶ = 1631557 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a plaindrome in base 15.

It is a junction number, because it is equal to n+sod(n) for n = 1631593 and 1631602.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1631629) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7376 + ... + 7593.

It is an arithmetic number, because the mean of its divisors is an integer number (411675).

2^1631621 is an apocalyptic number.

It is an amenable number.

1631621 is a deficient number, since it is larger than the sum of its proper divisors (15079).

1631621 is a wasteful number, since it uses less digits than its factorization.

1631621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15078.

The product of its digits is 216, while the sum is 20.

The square root of 1631621 is about 1277.3492083217. The cubic root of 1631621 is about 117.7261917266.

Adding to 1631621 its reverse (1261361), we get a palindrome (2892982).

The spelling of 1631621 in words is "one million, six hundred thirty-one thousand, six hundred twenty-one".