21202420157 has 2 divisors, whose sum is σ = 21202420158. Its totient is φ = 21202420156.

The previous prime is 21202420123. The next prime is 21202420243. The reversal of 21202420157 is 75102420212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18998211556 + 2204208601 = 137834^2 + 46949^2 .

It is a cyclic number.

It is not a de Polignac number, because 21202420157 - 2¹² = 21202416061 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21202425157) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10601210078 + 10601210079.

It is an arithmetic number, because the mean of its divisors is an integer number (10601210079).

Almost surely, 2^21202420157 is an apocalyptic number.

It is an amenable number.

21202420157 is a deficient number, since it is larger than the sum of its proper divisors (1).

21202420157 is an equidigital number, since it uses as much as digits as its factorization.

21202420157 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2240, while the sum is 26.

Adding to 21202420157 its reverse (75102420212), we get a palindrome (96304840369).

The spelling of 21202420157 in words is "twenty-one billion, two hundred two million, four hundred twenty thousand, one hundred fifty-seven".