21519168901 has 2 divisors, whose sum is σ = 21519168902. Its totient is φ = 21519168900.

The previous prime is 21519168893. The next prime is 21519168917. The reversal of 21519168901 is 10986191512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20014892676 + 1504276225 = 141474^2 + 38785^2 .

It is a cyclic number.

It is not a de Polignac number, because 21519168901 - 2³ = 21519168893 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21519168301) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10759584450 + 10759584451.

It is an arithmetic number, because the mean of its divisors is an integer number (10759584451).

Almost surely, 2^21519168901 is an apocalyptic number.

It is an amenable number.

21519168901 is a deficient number, since it is larger than the sum of its proper divisors (1).

21519168901 is an equidigital number, since it uses as much as digits as its factorization.

21519168901 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 38880, while the sum is 43.

The spelling of 21519168901 in words is "twenty-one billion, five hundred nineteen million, one hundred sixty-eight thousand, nine hundred one".