21103232621 has 2 divisors, whose sum is σ = 21103232622. Its totient is φ = 21103232620.

The previous prime is 21103232617. The next prime is 21103232629. The reversal of 21103232621 is 12623230112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20033288521 + 1069944100 = 141539^2 + 32710^2 .

It is a cyclic number.

It is not a de Polignac number, because 21103232621 - 2² = 21103232617 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21103232629) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10551616310 + 10551616311.

It is an arithmetic number, because the mean of its divisors is an integer number (10551616311).

Almost surely, 2^21103232621 is an apocalyptic number.

It is an amenable number.

21103232621 is a deficient number, since it is larger than the sum of its proper divisors (1).

21103232621 is an equidigital number, since it uses as much as digits as its factorization.

21103232621 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 864, while the sum is 23.

Adding to 21103232621 its reverse (12623230112), we get a palindrome (33726462733).

The spelling of 21103232621 in words is "twenty-one billion, one hundred three million, two hundred thirty-two thousand, six hundred twenty-one".