21847691 has 2 divisors, whose sum is σ = 21847692. Its totient is φ = 21847690.

The previous prime is 21847627. The next prime is 21847733. The reversal of 21847691 is 19674812.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21847691 - 2⁶ = 21847627 is a prime.

It is not a weakly prime, because it can be changed into another prime (21840691) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10923845 + 10923846.

It is an arithmetic number, because the mean of its divisors is an integer number (10923846).

Almost surely, 2^21847691 is an apocalyptic number.

21847691 is a deficient number, since it is larger than the sum of its proper divisors (1).

21847691 is an equidigital number, since it uses as much as digits as its factorization.

21847691 is an evil number, because the sum of its binary digits is even.

The product of its digits is 24192, while the sum is 38.

The square root of 21847691 is about 4674.1513668259. The cubic root of 21847691 is about 279.5558050508. Note that the first 3 decimals are identical.

The spelling of 21847691 in words is "twenty-one million, eight hundred forty-seven thousand, six hundred ninety-one".