21001500521 has 2 divisors, whose sum is σ = 21001500522. Its totient is φ = 21001500520.

The previous prime is 21001500463. The next prime is 21001500563. The reversal of 21001500521 is 12500510012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15460186921 + 5541313600 = 124339^2 + 74440^2 .

It is a cyclic number.

It is not a de Polignac number, because 21001500521 - 2¹⁴ = 21001484137 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21001500521.

It is not a weakly prime, because it can be changed into another prime (21001500581) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10500750260 + 10500750261.

It is an arithmetic number, because the mean of its divisors is an integer number (10500750261).

Almost surely, 2^21001500521 is an apocalyptic number.

It is an amenable number.

21001500521 is a deficient number, since it is larger than the sum of its proper divisors (1).

21001500521 is an equidigital number, since it uses as much as digits as its factorization.

21001500521 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 100, while the sum is 17.

The spelling of 21001500521 in words is "twenty-one billion, one million, five hundred thousand, five hundred twenty-one".