21530077 has 2 divisors, whose sum is σ = 21530078. Its totient is φ = 21530076.

The previous prime is 21530017. The next prime is 21530099. The reversal of 21530077 is 77003512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21288996 + 241081 = 4614^2 + 491^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21530077 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21530017) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10765038 + 10765039.

It is an arithmetic number, because the mean of its divisors is an integer number (10765039).

Almost surely, 2^21530077 is an apocalyptic number.

It is an amenable number.

21530077 is a deficient number, since it is larger than the sum of its proper divisors (1).

21530077 is an equidigital number, since it uses as much as digits as its factorization.

21530077 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1470, while the sum is 25.

The square root of 21530077 is about 4640.0514005774. The cubic root of 21530077 is about 278.1944923688.

Adding to 21530077 its reverse (77003512), we get a palindrome (98533589).

The spelling of 21530077 in words is "twenty-one million, five hundred thirty thousand, seventy-seven".