21197767 has 2 divisors, whose sum is σ = 21197768. Its totient is φ = 21197766.

The previous prime is 21197731. The next prime is 21197773. The reversal of 21197767 is 76779112.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21197767 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21197167) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10598883 + 10598884.

It is an arithmetic number, because the mean of its divisors is an integer number (10598884).

Almost surely, 2^21197767 is an apocalyptic number.

21197767 is a deficient number, since it is larger than the sum of its proper divisors (1).

21197767 is an equidigital number, since it uses as much as digits as its factorization.

21197767 is an evil number, because the sum of its binary digits is even.

The product of its digits is 37044, while the sum is 40.

The square root of 21197767 is about 4604.1032785983. The cubic root of 21197767 is about 276.7557831336.

The spelling of 21197767 in words is "twenty-one million, one hundred ninety-seven thousand, seven hundred sixty-seven".