21669667 has 2 divisors, whose sum is σ = 21669668. Its totient is φ = 21669666.

The previous prime is 21669649. The next prime is 21669673. The reversal of 21669667 is 76696612.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21669667 - 2¹⁵ = 21636899 is a prime.

It is not a weakly prime, because it can be changed into another prime (21669677) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10834833 + 10834834.

It is an arithmetic number, because the mean of its divisors is an integer number (10834834).

Almost surely, 2^21669667 is an apocalyptic number.

21669667 is a deficient number, since it is larger than the sum of its proper divisors (1).

21669667 is an equidigital number, since it uses as much as digits as its factorization.

21669667 is an evil number, because the sum of its binary digits is even.

The product of its digits is 163296, while the sum is 43.

The square root of 21669667 is about 4655.0689575988. The cubic root of 21669667 is about 278.7944212556.

The spelling of 21669667 in words is "twenty-one million, six hundred sixty-nine thousand, six hundred sixty-seven".