99210821 has 2 divisors, whose sum is σ = 99210822. Its totient is φ = 99210820.

The previous prime is 99210781. The next prime is 99210851. The reversal of 99210821 is 12801299.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 52780225 + 46430596 = 7265^2 + 6814^2 .

It is a cyclic number.

It is not a de Polignac number, because 99210821 - 2¹⁰ = 99209797 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (99210851) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 49605410 + 49605411.

It is an arithmetic number, because the mean of its divisors is an integer number (49605411).

Almost surely, 2^99210821 is an apocalyptic number.

It is an amenable number.

99210821 is a deficient number, since it is larger than the sum of its proper divisors (1).

99210821 is an equidigital number, since it uses as much as digits as its factorization.

99210821 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2592, while the sum is 32.

The square root of 99210821 is about 9960.4628908500. The cubic root of 99210821 is about 462.9346423954.

The spelling of 99210821 in words is "ninety-nine million, two hundred ten thousand, eight hundred twenty-one".