21519101 has 2 divisors, whose sum is σ = 21519102. Its totient is φ = 21519100.

The previous prime is 21519083. The next prime is 21519103. The reversal of 21519101 is 10191512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19272100 + 2247001 = 4390^2 + 1499^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21519101 is a prime.

Together with 21519103, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21519103) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10759550 + 10759551.

It is an arithmetic number, because the mean of its divisors is an integer number (10759551).

Almost surely, 2^21519101 is an apocalyptic number.

It is an amenable number.

21519101 is a deficient number, since it is larger than the sum of its proper divisors (1).

21519101 is an equidigital number, since it uses as much as digits as its factorization.

21519101 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 90, while the sum is 20.

The square root of 21519101 is about 4638.8685042799. The cubic root of 21519101 is about 278.1472099589.

The spelling of 21519101 in words is "twenty-one million, five hundred nineteen thousand, one hundred one".