21019967 has 2 divisors, whose sum is σ = 21019968. Its totient is φ = 21019966.

The previous prime is 21019963. The next prime is 21019969. The reversal of 21019967 is 76991012.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21019967 - 2² = 21019963 is a prime.

Together with 21019969, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21019961) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10509983 + 10509984.

It is an arithmetic number, because the mean of its divisors is an integer number (10509984).

Almost surely, 2^21019967 is an apocalyptic number.

21019967 is a deficient number, since it is larger than the sum of its proper divisors (1).

21019967 is an equidigital number, since it uses as much as digits as its factorization.

21019967 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6804, while the sum is 35.

The square root of 21019967 is about 4584.7537556558. The cubic root of 21019967 is about 275.9798303191.

The spelling of 21019967 in words is "twenty-one million, nineteen thousand, nine hundred sixty-seven".