21547557379 has 2 divisors, whose sum is σ = 21547557380. Its totient is φ = 21547557378.

The previous prime is 21547557359. The next prime is 21547557391. The reversal of 21547557379 is 97375574512.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21547557379 - 2⁵ = 21547557347 is a prime.

It is not a weakly prime, because it can be changed into another prime (21547557359) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10773778689 + 10773778690.

It is an arithmetic number, because the mean of its divisors is an integer number (10773778690).

Almost surely, 2^21547557379 is an apocalyptic number.

21547557379 is a deficient number, since it is larger than the sum of its proper divisors (1).

21547557379 is an equidigital number, since it uses as much as digits as its factorization.

21547557379 is an evil number, because the sum of its binary digits is even.

The product of its digits is 9261000, while the sum is 55.

The spelling of 21547557379 in words is "twenty-one billion, five hundred forty-seven million, five hundred fifty-seven thousand, three hundred seventy-nine".