21649967 has 2 divisors, whose sum is σ = 21649968. Its totient is φ = 21649966.

The previous prime is 21649963. The next prime is 21650011. The reversal of 21649967 is 76994612.

It is an a-pointer prime, because the next prime (21650011) can be obtained adding 21649967 to its sum of digits (44).

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21649967 - 2² = 21649963 is a prime.

It is a super-2 number, since 2×21649967² = 937442142202178, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21649961) 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, 10824983 + 10824984.

It is an arithmetic number, because the mean of its divisors is an integer number (10824984).

Almost surely, 2^21649967 is an apocalyptic number.

21649967 is a deficient number, since it is larger than the sum of its proper divisors (1).

21649967 is an equidigital number, since it uses as much as digits as its factorization.

21649967 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 163296, while the sum is 44.

The square root of 21649967 is about 4652.9525035186. The cubic root of 21649967 is about 278.7099111847.

The spelling of 21649967 in words is "twenty-one million, six hundred forty-nine thousand, nine hundred sixty-seven".