2131505621 has 4 divisors (see below), whose sum is σ = 2436006432. Its totient is φ = 1827004812.

The previous prime is 2131505617. The next prime is 2131505627. The reversal of 2131505621 is 1265051312.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 2131505621 - 2² = 2131505617 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2131505627) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 152250395 + ... + 152250408.

It is an arithmetic number, because the mean of its divisors is an integer number (609001608).

Almost surely, 2^2131505621 is an apocalyptic number.

It is an amenable number.

2131505621 is a deficient number, since it is larger than the sum of its proper divisors (304500811).

2131505621 is an equidigital number, since it uses as much as digits as its factorization.

2131505621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 304500810.

The product of its (nonzero) digits is 1800, while the sum is 26.

The square root of 2131505621 is about 46168.2317291880. The cubic root of 2131505621 is about 1286.9514417573.

Adding to 2131505621 its reverse (1265051312), we get a palindrome (3396556933).

The spelling of 2131505621 in words is "two billion, one hundred thirty-one million, five hundred five thousand, six hundred twenty-one".