21747493 has 2 divisors, whose sum is σ = 21747494. Its totient is φ = 21747492.

The previous prime is 21747449. The next prime is 21747499. The reversal of 21747493 is 39474712.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10975969 + 10771524 = 3313^2 + 3282^2 .

It is a cyclic number.

It is not a de Polignac number, because 21747493 - 2⁹ = 21746981 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21747499) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10873746 + 10873747.

It is an arithmetic number, because the mean of its divisors is an integer number (10873747).

Almost surely, 2^21747493 is an apocalyptic number.

It is an amenable number.

21747493 is a deficient number, since it is larger than the sum of its proper divisors (1).

21747493 is an equidigital number, since it uses as much as digits as its factorization.

21747493 is an evil number, because the sum of its binary digits is even.

The product of its digits is 42336, while the sum is 37.

The square root of 21747493 is about 4663.4207401863. The cubic root of 21747493 is about 279.1277832629.

The spelling of 21747493 in words is "twenty-one million, seven hundred forty-seven thousand, four hundred ninety-three".