2145542821 has 2 divisors, whose sum is σ = 2145542822. Its totient is φ = 2145542820.

The previous prime is 2145542807. The next prime is 2145542857. The reversal of 2145542821 is 1282455412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1564202500 + 581340321 = 39550^2 + 24111^2 .

It is a cyclic number.

It is not a de Polignac number, because 2145542821 - 2⁹ = 2145542309 is a prime.

It is a super-3 number, since 3×2145542821³ (a number of 29 digits) contains 333 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2145540821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1072771410 + 1072771411.

It is an arithmetic number, because the mean of its divisors is an integer number (1072771411).

Almost surely, 2^2145542821 is an apocalyptic number.

It is an amenable number.

2145542821 is a deficient number, since it is larger than the sum of its proper divisors (1).

2145542821 is an equidigital number, since it uses as much as digits as its factorization.

2145542821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 25600, while the sum is 34.

The square root of 2145542821 is about 46320.0045444730. The cubic root of 2145542821 is about 1289.7703697588.

The spelling of 2145542821 in words is "two billion, one hundred forty-five million, five hundred forty-two thousand, eight hundred twenty-one".