21827491 has 10 divisors (see below), whose sum is σ = 25466692. Its totient is φ = 18707220.

The previous prime is 21827489. The next prime is 21827497. The reversal of 21827491 is 19472812.

It is not a de Polignac number, because 21827491 - 2¹ = 21827489 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21827497) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 2145 + ... + 6946.

Almost surely, 2^21827491 is an apocalyptic number.

21827491 is a deficient number, since it is larger than the sum of its proper divisors (3639201).

21827491 is an frugal number, since it uses more digits than its factorization.

21827491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9119 (or 9098 counting only the distinct ones).

The product of its digits is 8064, while the sum is 34.

The square root of 21827491 is about 4671.9900470784. The cubic root of 21827491 is about 279.4696209847.

The spelling of 21827491 in words is "twenty-one million, eight hundred twenty-seven thousand, four hundred ninety-one".