21072229 has 2 divisors, whose sum is σ = 21072230. Its totient is φ = 21072228.

The previous prime is 21072211. The next prime is 21072239. The reversal of 21072229 is 92227012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17032129 + 4040100 = 4127^2 + 2010^2 .

It is a cyclic number.

It is not a de Polignac number, because 21072229 - 2⁷ = 21072101 is a prime.

It is equal to p_1334266 and since 21072229 and 1334266 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21072239) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10536114 + 10536115.

It is an arithmetic number, because the mean of its divisors is an integer number (10536115).

Almost surely, 2^21072229 is an apocalyptic number.

It is an amenable number.

21072229 is a deficient number, since it is larger than the sum of its proper divisors (1).

21072229 is an equidigital number, since it uses as much as digits as its factorization.

21072229 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1008, while the sum is 25.

The square root of 21072229 is about 4590.4497600998. The cubic root of 21072229 is about 276.2083641515.

The spelling of 21072229 in words is "twenty-one million, seventy-two thousand, two hundred twenty-nine".