99780521 has 2 divisors, whose sum is σ = 99780522. Its totient is φ = 99780520.

The previous prime is 99780517. The next prime is 99780523. The reversal of 99780521 is 12508799.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 99780121 + 400 = 9989^2 + 20^2 .

It is a cyclic number.

It is not a de Polignac number, because 99780521 - 2² = 99780517 is a prime.

Together with 99780523, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (99780523) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 49890260 + 49890261.

It is an arithmetic number, because the mean of its divisors is an integer number (49890261).

Almost surely, 2^99780521 is an apocalyptic number.

It is an amenable number.

99780521 is a deficient number, since it is larger than the sum of its proper divisors (1).

99780521 is an equidigital number, since it uses as much as digits as its factorization.

99780521 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 45360, while the sum is 41.

The square root of 99780521 is about 9989.0200220042. The cubic root of 99780521 is about 463.8190575326.

It can be divided in two parts, 997 and 80521, that added together give a palindrome (81518).

The spelling of 99780521 in words is "ninety-nine million, seven hundred eighty thousand, five hundred twenty-one".