21263623 has 2 divisors, whose sum is σ = 21263624. Its totient is φ = 21263622.

The previous prime is 21263621. The next prime is 21263647. The reversal of 21263623 is 32636212.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21263623 - 2¹ = 21263621 is a prime.

It is a super-2 number, since 2×21263623² = 904283326172258, which contains 22 as substring.

Together with 21263621, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21263621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10631811 + 10631812.

It is an arithmetic number, because the mean of its divisors is an integer number (10631812).

Almost surely, 2^21263623 is an apocalyptic number.

21263623 is a deficient number, since it is larger than the sum of its proper divisors (1).

21263623 is an equidigital number, since it uses as much as digits as its factorization.

21263623 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2592, while the sum is 25.

The square root of 21263623 is about 4611.2496137164. The cubic root of 21263623 is about 277.0420898129.

Adding to 21263623 its reverse (32636212), we get a palindrome (53899835).

It can be divided in two parts, 212636 and 23, that multiplied together give a triangular number (4890628 = T₃₁₂₇).

The spelling of 21263623 in words is "twenty-one million, two hundred sixty-three thousand, six hundred twenty-three".