21532501 has 2 divisors, whose sum is σ = 21532502. Its totient is φ = 21532500.

The previous prime is 21532499. The next prime is 21532513. The reversal of 21532501 is 10523512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11458225 + 10074276 = 3385^2 + 3174^2 .

It is a cyclic number.

It is not a de Polignac number, because 21532501 - 2¹ = 21532499 is a prime.

Together with 21532499, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21532541) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10766250 + 10766251.

It is an arithmetic number, because the mean of its divisors is an integer number (10766251).

Almost surely, 2^21532501 is an apocalyptic number.

It is an amenable number.

21532501 is a deficient number, since it is larger than the sum of its proper divisors (1).

21532501 is an equidigital number, since it uses as much as digits as its factorization.

21532501 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 300, while the sum is 19.

The square root of 21532501 is about 4640.3125972288. The cubic root of 21532501 is about 278.2049323089.

The spelling of 21532501 in words is "twenty-one million, five hundred thirty-two thousand, five hundred one".