1621931 has 2 divisors, whose sum is σ = 1621932. Its totient is φ = 1621930.

The previous prime is 1621909. The next prime is 1621933. The reversal of 1621931 is 1391261.

It is a happy number.

It is a strong prime.

It is an emirp because it is prime and its reverse (1391261) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1621931 - 2¹⁴ = 1605547 is a prime.

It is a super-2 number, since 2×1621931² = 5261320337522, which contains 22 as substring.

Together with 1621933, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 1621897 and 1621906.

It is not a weakly prime, because it can be changed into another prime (1621933) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 810965 + 810966.

It is an arithmetic number, because the mean of its divisors is an integer number (810966).

2^1621931 is an apocalyptic number.

1621931 is a deficient number, since it is larger than the sum of its proper divisors (1).

1621931 is an equidigital number, since it uses as much as digits as its factorization.

1621931 is an evil number, because the sum of its binary digits is even.

The product of its digits is 324, while the sum is 23.

The square root of 1621931 is about 1273.5505486631. The cubic root of 1621931 is about 117.4926749621.

It can be divided in two parts, 1621 and 931, that added together give a palindrome (2552).

The spelling of 1621931 in words is "one million, six hundred twenty-one thousand, nine hundred thirty-one".