33131621 has 2 divisors, whose sum is σ = 33131622. Its totient is φ = 33131620.

The previous prime is 33131599. The next prime is 33131639. The reversal of 33131621 is 12613133.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 32330596 + 801025 = 5686^2 + 895^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-33131621 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 33131593 and 33131602.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (33131641) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 16565810 + 16565811.

It is an arithmetic number, because the mean of its divisors is an integer number (16565811).

Almost surely, 2^33131621 is an apocalyptic number.

It is an amenable number.

33131621 is a deficient number, since it is larger than the sum of its proper divisors (1).

33131621 is an equidigital number, since it uses as much as digits as its factorization.

33131621 is an evil number, because the sum of its binary digits is even.

The product of its digits is 324, while the sum is 20.

The square root of 33131621 is about 5756.0073835950. The cubic root of 33131621 is about 321.1793106031.

Adding to 33131621 its reverse (12613133), we get a palindrome (45744754).

The spelling of 33131621 in words is "thirty-three million, one hundred thirty-one thousand, six hundred twenty-one".