21020244148457 has 2 divisors, whose sum is σ = 21020244148458. Its totient is φ = 21020244148456.

The previous prime is 21020244148441. The next prime is 21020244148489. The reversal of 21020244148457 is 75484144202012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18893835663616 + 2126408484841 = 4346704^2 + 1458221^2 .

It is a cyclic number.

It is not a de Polignac number, because 21020244148457 - 2⁴ = 21020244148441 is a prime.

It is not a weakly prime, because it can be changed into another prime (21020244148417) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10510122074228 + 10510122074229.

It is an arithmetic number, because the mean of its divisors is an integer number (10510122074229).

Almost surely, 2^{21020244148457} is an apocalyptic number.

It is an amenable number.

21020244148457 is a deficient number, since it is larger than the sum of its proper divisors (1).

21020244148457 is an equidigital number, since it uses as much as digits as its factorization.

21020244148457 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 573440, while the sum is 44.

The spelling of 21020244148457 in words is "twenty-one trillion, twenty billion, two hundred forty-four million, one hundred forty-eight thousand, four hundred fifty-seven".