2145421561 has 2 divisors, whose sum is σ = 2145421562. Its totient is φ = 2145421560.

The previous prime is 2145421559. The next prime is 2145421589. The reversal of 2145421561 is 1651245412.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1612504336 + 532917225 = 40156^2 + 23085^2 .

It is a cyclic number.

It is not a de Polignac number, because 2145421561 - 2¹ = 2145421559 is a prime.

Together with 2145421559, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (2145422561) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1072710780 + 1072710781.

It is an arithmetic number, because the mean of its divisors is an integer number (1072710781).

Almost surely, 2^2145421561 is an apocalyptic number.

It is an amenable number.

2145421561 is a deficient number, since it is larger than the sum of its proper divisors (1).

2145421561 is an equidigital number, since it uses as much as digits as its factorization.

2145421561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 9600, while the sum is 31.

The square root of 2145421561 is about 46318.6955882827. The cubic root of 2145421561 is about 1289.7460712456.

Adding to 2145421561 its reverse (1651245412), we get a palindrome (3796666973).

The spelling of 2145421561 in words is "two billion, one hundred forty-five million, four hundred twenty-one thousand, five hundred sixty-one".