99972221 has 2 divisors, whose sum is σ = 99972222. Its totient is φ = 99972220.

The previous prime is 99972163. The next prime is 99972233. The reversal of 99972221 is 12227999.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 63840100 + 36132121 = 7990^2 + 6011^2 .

It is a cyclic number.

It is not a de Polignac number, because 99972221 - 2⁶ = 99972157 is a prime.

It is equal to p_5759951 and since 99972221 and 5759951 have the same sum of digits, it is a Honaker prime.

It is a nialpdrome in base 10.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (99932221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 49986110 + 49986111.

It is an arithmetic number, because the mean of its divisors is an integer number (49986111).

Almost surely, 2^99972221 is an apocalyptic number.

It is an amenable number.

99972221 is a deficient number, since it is larger than the sum of its proper divisors (1).

99972221 is an equidigital number, since it uses as much as digits as its factorization.

99972221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 40824, while the sum is 41.

The square root of 99972221 is about 9998.6109535275. The cubic root of 99972221 is about 464.1158998155.

The spelling of 99972221 in words is "ninety-nine million, nine hundred seventy-two thousand, two hundred twenty-one".