21505332379 has 2 divisors, whose sum is σ = 21505332380. Its totient is φ = 21505332378.

The previous prime is 21505332377. The next prime is 21505332439. The reversal of 21505332379 is 97323350512.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21505332379 - 2¹ = 21505332377 is a prime.

Together with 21505332377, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21505332377) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10752666189 + 10752666190.

It is an arithmetic number, because the mean of its divisors is an integer number (10752666190).

Almost surely, 2^21505332379 is an apocalyptic number.

21505332379 is a deficient number, since it is larger than the sum of its proper divisors (1).

21505332379 is an equidigital number, since it uses as much as digits as its factorization.

21505332379 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 170100, while the sum is 40.

The spelling of 21505332379 in words is "twenty-one billion, five hundred five million, three hundred thirty-two thousand, three hundred seventy-nine".