21537671 has 2 divisors, whose sum is σ = 21537672. Its totient is φ = 21537670.

The previous prime is 21537667. The next prime is 21537673. The reversal of 21537671 is 17673512.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21537671 - 2² = 21537667 is a prime.

Together with 21537673, 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 (21537673) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10768835 + 10768836.

It is an arithmetic number, because the mean of its divisors is an integer number (10768836).

Almost surely, 2^21537671 is an apocalyptic number.

21537671 is a deficient number, since it is larger than the sum of its proper divisors (1).

21537671 is an equidigital number, since it uses as much as digits as its factorization.

21537671 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 8820, while the sum is 32.

The square root of 21537671 is about 4640.8696383329. The cubic root of 21537671 is about 278.2271963955.

The spelling of 21537671 in words is "twenty-one million, five hundred thirty-seven thousand, six hundred seventy-one".