21369847 has 2 divisors, whose sum is σ = 21369848. Its totient is φ = 21369846.

The previous prime is 21369811. The next prime is 21369853. The reversal of 21369847 is 74896312.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21369847 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21369247) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10684923 + 10684924.

It is an arithmetic number, because the mean of its divisors is an integer number (10684924).

Almost surely, 2^21369847 is an apocalyptic number.

21369847 is a deficient number, since it is larger than the sum of its proper divisors (1).

21369847 is an equidigital number, since it uses as much as digits as its factorization.

21369847 is an evil number, because the sum of its binary digits is even.

The product of its digits is 72576, while the sum is 40.

The square root of 21369847 is about 4622.7531839803. The cubic root of 21369847 is about 277.5026518157.

The spelling of 21369847 in words is "twenty-one million, three hundred sixty-nine thousand, eight hundred forty-seven".