133631021 has 4 divisors (see below), whose sum is σ = 134482332. Its totient is φ = 132779712.

The previous prime is 133630997. The next prime is 133631023. The reversal of 133631021 is 120136331.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 21058921 + 112572100 = 4589^2 + 10610^2 .

It is a cyclic number.

It is not a de Polignac number, because 133631021 - 2²² = 129436717 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 133630984 and 133631002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (133631023) 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, 425420 + ... + 425733.

It is an arithmetic number, because the mean of its divisors is an integer number (33620583).

Almost surely, 2^133631021 is an apocalyptic number.

It is an amenable number.

133631021 is a deficient number, since it is larger than the sum of its proper divisors (851311).

133631021 is an equidigital number, since it uses as much as digits as its factorization.

133631021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 851310.

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

The square root of 133631021 is about 11559.8884510189. Note that the first 3 decimals coincide. The cubic root of 133631021 is about 511.2528737711.

Adding to 133631021 its reverse (120136331), we get a palindrome (253767352).

It can be divided in two parts, 1336310 and 21, that added together give a palindrome (1336331).

The spelling of 133631021 in words is "one hundred thirty-three million, six hundred thirty-one thousand, twenty-one".