21501967 has 2 divisors, whose sum is σ = 21501968. Its totient is φ = 21501966.

The previous prime is 21501943. The next prime is 21502001. The reversal of 21501967 is 76910512.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21501967 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21511967) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10750983 + 10750984.

It is an arithmetic number, because the mean of its divisors is an integer number (10750984).

Almost surely, 2^21501967 is an apocalyptic number.

21501967 is a deficient number, since it is larger than the sum of its proper divisors (1).

21501967 is an equidigital number, since it uses as much as digits as its factorization.

21501967 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3780, while the sum is 31.

The square root of 21501967 is about 4637.0213499616. The cubic root of 21501967 is about 278.0733679688.

The spelling of 21501967 in words is "twenty-one million, five hundred one thousand, nine hundred sixty-seven".