21400321057 has 2 divisors, whose sum is σ = 21400321058. Its totient is φ = 21400321056.

The previous prime is 21400321049. The next prime is 21400321073. The reversal of 21400321057 is 75012300412.

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., 21374147601 + 26173456 = 146199^2 + 5116^2 .

It is a cyclic number.

It is not a de Polignac number, because 21400321057 - 2³ = 21400321049 is a prime.

It is not a weakly prime, because it can be changed into another prime (21400321087) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10700160528 + 10700160529.

It is an arithmetic number, because the mean of its divisors is an integer number (10700160529).

Almost surely, 2^21400321057 is an apocalyptic number.

It is an amenable number.

21400321057 is a deficient number, since it is larger than the sum of its proper divisors (1).

21400321057 is an equidigital number, since it uses as much as digits as its factorization.

21400321057 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1680, while the sum is 25.

Adding to 21400321057 its reverse (75012300412), we get a palindrome (96412621469).

The spelling of 21400321057 in words is "twenty-one billion, four hundred million, three hundred twenty-one thousand, fifty-seven".