21502969 has 2 divisors, whose sum is σ = 21502970. Its totient is φ = 21502968.

The previous prime is 21502961. The next prime is 21502979. The reversal of 21502969 is 96920512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21040569 + 462400 = 4587^2 + 680^2 .

It is a cyclic number.

It is not a de Polignac number, because 21502969 - 2³ = 21502961 is a prime.

It is a super-2 number, since 2×21502969² = 924755351629922, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21502961) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10751484 + 10751485.

It is an arithmetic number, because the mean of its divisors is an integer number (10751485).

Almost surely, 2^21502969 is an apocalyptic number.

It is an amenable number.

21502969 is a deficient number, since it is larger than the sum of its proper divisors (1).

21502969 is an equidigital number, since it uses as much as digits as its factorization.

21502969 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 9720, while the sum is 34.

The square root of 21502969 is about 4637.1293921994. The cubic root of 21502969 is about 278.0776873440.

The spelling of 21502969 in words is "twenty-one million, five hundred two thousand, nine hundred sixty-nine".