21506101 has 2 divisors, whose sum is σ = 21506102. Its totient is φ = 21506100.

The previous prime is 21506083. The next prime is 21506131. The reversal of 21506101 is 10160512.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14243076 + 7263025 = 3774^2 + 2695^2 .

It is a cyclic number.

It is not a de Polignac number, because 21506101 - 2¹¹ = 21504053 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21506131) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10753050 + 10753051.

It is an arithmetic number, because the mean of its divisors is an integer number (10753051).

Almost surely, 2^21506101 is an apocalyptic number.

It is an amenable number.

21506101 is a deficient number, since it is larger than the sum of its proper divisors (1).

21506101 is an equidigital number, since it uses as much as digits as its factorization.

21506101 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 60, while the sum is 16.

The square root of 21506101 is about 4637.4670888320. The cubic root of 21506101 is about 278.0911877593.

Adding to 21506101 its reverse (10160512), we get a palindrome (31666613).

The spelling of 21506101 in words is "twenty-one million, five hundred six thousand, one hundred one".