21623101 has 2 divisors, whose sum is σ = 21623102. Its totient is φ = 21623100.

The previous prime is 21623081. The next prime is 21623131. The reversal of 21623101 is 10132612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21483225 + 139876 = 4635^2 + 374^2 .

It is a cyclic number.

It is not a de Polignac number, because 21623101 - 2¹¹ = 21621053 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21623131) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10811550 + 10811551.

It is an arithmetic number, because the mean of its divisors is an integer number (10811551).

Almost surely, 2^21623101 is an apocalyptic number.

It is an amenable number.

21623101 is a deficient number, since it is larger than the sum of its proper divisors (1).

21623101 is an equidigital number, since it uses as much as digits as its factorization.

21623101 is an evil number, because the sum of its binary digits is even.

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

The square root of 21623101 is about 4650.0646232069. The cubic root of 21623101 is about 278.5945773694.

Adding to 21623101 its reverse (10132612), we get a palindrome (31755713).

The spelling of 21623101 in words is "twenty-one million, six hundred twenty-three thousand, one hundred one".