21144430157 has 2 divisors, whose sum is σ = 21144430158. Its totient is φ = 21144430156.

The previous prime is 21144430147. The next prime is 21144430247. The reversal of 21144430157 is 75103444112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15746736196 + 5397693961 = 125486^2 + 73469^2 .

It is a cyclic number.

It is not a de Polignac number, because 21144430157 - 2¹⁶ = 21144364621 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21144430147) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10572215078 + 10572215079.

It is an arithmetic number, because the mean of its divisors is an integer number (10572215079).

Almost surely, 2^21144430157 is an apocalyptic number.

It is an amenable number.

21144430157 is a deficient number, since it is larger than the sum of its proper divisors (1).

21144430157 is an equidigital number, since it uses as much as digits as its factorization.

21144430157 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 13440, while the sum is 32.

Adding to 21144430157 its reverse (75103444112), we get a palindrome (96247874269).

The spelling of 21144430157 in words is "twenty-one billion, one hundred forty-four million, four hundred thirty thousand, one hundred fifty-seven".