21712469 has 2 divisors, whose sum is σ = 21712470. Its totient is φ = 21712468.

The previous prime is 21712423. The next prime is 21712477. The reversal of 21712469 is 96421712.

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., 15311569 + 6400900 = 3913^2 + 2530^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21712469 is a prime.

It is a super-2 number, since 2×21712469² = 942862620151922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21712169) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10856234 + 10856235.

It is an arithmetic number, because the mean of its divisors is an integer number (10856235).

Almost surely, 2^21712469 is an apocalyptic number.

It is an amenable number.

21712469 is a deficient number, since it is larger than the sum of its proper divisors (1).

21712469 is an equidigital number, since it uses as much as digits as its factorization.

21712469 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6048, while the sum is 32.

The square root of 21712469 is about 4659.6640436838. The cubic root of 21712469 is about 278.9778590961.

The spelling of 21712469 in words is "twenty-one million, seven hundred twelve thousand, four hundred sixty-nine".