21420031057 has 2 divisors, whose sum is σ = 21420031058. Its totient is φ = 21420031056.

The previous prime is 21420031001. The next prime is 21420031067. The reversal of 21420031057 is 75013002412.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19966820416 + 1453210641 = 141304^2 + 38121^2 .

It is a cyclic number.

It is not a de Polignac number, because 21420031057 - 2²³ = 21411642449 is a prime.

It is not a weakly prime, because it can be changed into another prime (21420031067) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10710015528 + 10710015529.

It is an arithmetic number, because the mean of its divisors is an integer number (10710015529).

Almost surely, 2^21420031057 is an apocalyptic number.

It is an amenable number.

21420031057 is a deficient number, since it is larger than the sum of its proper divisors (1).

21420031057 is an equidigital number, since it uses as much as digits as its factorization.

21420031057 is an odious number, because the sum of its binary digits is odd.

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

Adding to 21420031057 its reverse (75013002412), we get a palindrome (96433033469).

The spelling of 21420031057 in words is "twenty-one billion, four hundred twenty million, thirty-one thousand, fifty-seven".