21144340157 has 2 divisors, whose sum is σ = 21144340158. Its totient is φ = 21144340156.

The previous prime is 21144340141. The next prime is 21144340169. The reversal of 21144340157 is 75104344112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20645666596 + 498673561 = 143686^2 + 22331^2 .

It is a cyclic number.

It is not a de Polignac number, because 21144340157 - 2⁴ = 21144340141 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21144340117) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10572170078 + 10572170079.

It is an arithmetic number, because the mean of its divisors is an integer number (10572170079).

Almost surely, 2^21144340157 is an apocalyptic number.

It is an amenable number.

21144340157 is a deficient number, since it is larger than the sum of its proper divisors (1).

21144340157 is an equidigital number, since it uses as much as digits as its factorization.

21144340157 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 21144340157 its reverse (75104344112), we get a palindrome (96248684269).

The spelling of 21144340157 in words is "twenty-one billion, one hundred forty-four million, three hundred forty thousand, one hundred fifty-seven".