21530497 has 2 divisors, whose sum is σ = 21530498. Its totient is φ = 21530496.

The previous prime is 21530489. The next prime is 21530513. The reversal of 21530497 is 79403512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18870336 + 2660161 = 4344^2 + 1631^2 .

It is a cyclic number.

It is not a de Polignac number, because 21530497 - 2³ = 21530489 is a prime.

It is not a weakly prime, because it can be changed into another prime (21530447) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10765248 + 10765249.

It is an arithmetic number, because the mean of its divisors is an integer number (10765249).

Almost surely, 2^21530497 is an apocalyptic number.

It is an amenable number.

21530497 is a deficient number, since it is larger than the sum of its proper divisors (1).

21530497 is an equidigital number, since it uses as much as digits as its factorization.

21530497 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 7560, while the sum is 31.

The square root of 21530497 is about 4640.0966584760. The cubic root of 21530497 is about 278.1963013254.

The spelling of 21530497 in words is "twenty-one million, five hundred thirty thousand, four hundred ninety-seven".