21540332377 has 2 divisors, whose sum is σ = 21540332378. Its totient is φ = 21540332376.

The previous prime is 21540332339. The next prime is 21540332381. The reversal of 21540332377 is 77323304512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17407899721 + 4132432656 = 131939^2 + 64284^2 .

It is a cyclic number.

It is not a de Polignac number, because 21540332377 - 2⁷ = 21540332249 is a prime.

It is not a weakly prime, because it can be changed into another prime (21540332327) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10770166188 + 10770166189.

It is an arithmetic number, because the mean of its divisors is an integer number (10770166189).

Almost surely, 2^21540332377 is an apocalyptic number.

It is an amenable number.

21540332377 is a deficient number, since it is larger than the sum of its proper divisors (1).

21540332377 is an equidigital number, since it uses as much as digits as its factorization.

21540332377 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 105840, while the sum is 37.

Adding to 21540332377 its reverse (77323304512), we get a palindrome (98863636889).

The spelling of 21540332377 in words is "twenty-one billion, five hundred forty million, three hundred thirty-two thousand, three hundred seventy-seven".