21623011 has 4 divisors (see below), whose sum is σ = 21896800. Its totient is φ = 21349224.

The previous prime is 21622999. The next prime is 21623057. The reversal of 21623011 is 11032612.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21623011 - 2⁷ = 21622883 is a prime.

It is a super-2 number, since 2×21623011² = 935109209412242, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21623081) 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 3 ways as a sum of consecutive naturals, for example, 136776 + ... + 136933.

It is an arithmetic number, because the mean of its divisors is an integer number (5474200).

Almost surely, 2^21623011 is an apocalyptic number.

21623011 is a deficient number, since it is larger than the sum of its proper divisors (273789).

21623011 is an equidigital number, since it uses as much as digits as its factorization.

21623011 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 273788.

The product of its (nonzero) digits is 72, while the sum is 16.

The square root of 21623011 is about 4650.0549459119. The cubic root of 21623011 is about 278.5941908453.

Adding to 21623011 its reverse (11032612), we get a palindrome (32655623).

The spelling of 21623011 in words is "twenty-one million, six hundred twenty-three thousand, eleven".