21849720157 has 2 divisors, whose sum is σ = 21849720158. Its totient is φ = 21849720156.

The previous prime is 21849720107. The next prime is 21849720181. The reversal of 21849720157 is 75102794812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15127524036 + 6722196121 = 122994^2 + 81989^2 .

It is a cyclic number.

It is not a de Polignac number, because 21849720157 - 2⁷ = 21849720029 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21849720107) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10924860078 + 10924860079.

It is an arithmetic number, because the mean of its divisors is an integer number (10924860079).

Almost surely, 2^21849720157 is an apocalyptic number.

It is an amenable number.

21849720157 is a deficient number, since it is larger than the sum of its proper divisors (1).

21849720157 is an equidigital number, since it uses as much as digits as its factorization.

21849720157 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 282240, while the sum is 46.

The spelling of 21849720157 in words is "twenty-one billion, eight hundred forty-nine million, seven hundred twenty thousand, one hundred fifty-seven".