21097547 has 2 divisors, whose sum is σ = 21097548. Its totient is φ = 21097546.

The previous prime is 21097513. The next prime is 21097567. The reversal of 21097547 is 74579012.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21097547 - 2⁸ = 21097291 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21097567) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10548773 + 10548774.

It is an arithmetic number, because the mean of its divisors is an integer number (10548774).

Almost surely, 2^21097547 is an apocalyptic number.

21097547 is a deficient number, since it is larger than the sum of its proper divisors (1).

21097547 is an equidigital number, since it uses as much as digits as its factorization.

21097547 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 17640, while the sum is 35.

The square root of 21097547 is about 4593.2066141205. The cubic root of 21097547 is about 276.3189400909.

The spelling of 21097547 in words is "twenty-one million, ninety-seven thousand, five hundred forty-seven".