21765347 has 2 divisors, whose sum is σ = 21765348. Its totient is φ = 21765346.

The previous prime is 21765329. The next prime is 21765391. The reversal of 21765347 is 74356712.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21765347 - 2²⁴ = 4988131 is a prime.

It is not a weakly prime, because it can be changed into another prime (21765307) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10882673 + 10882674.

It is an arithmetic number, because the mean of its divisors is an integer number (10882674).

Almost surely, 2^21765347 is an apocalyptic number.

21765347 is a deficient number, since it is larger than the sum of its proper divisors (1).

21765347 is an equidigital number, since it uses as much as digits as its factorization.

21765347 is an evil number, because the sum of its binary digits is even.

The product of its digits is 35280, while the sum is 35.

The square root of 21765347 is about 4665.3346075067. The cubic root of 21765347 is about 279.2041473797.

The spelling of 21765347 in words is "twenty-one million, seven hundred sixty-five thousand, three hundred forty-seven".