21951529 has 2 divisors, whose sum is σ = 21951530. Its totient is φ = 21951528.

The previous prime is 21951511. The next prime is 21951533. The reversal of 21951529 is 92515912.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21949225 + 2304 = 4685^2 + 48^2 .

It is a cyclic number.

It is not a de Polignac number, because 21951529 - 2⁵ = 21951497 is a prime.

It is a super-3 number, since 3×21951529³ (a number of 23 digits) contains 333 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21951494 and 21951503.

It is not a weakly prime, because it can be changed into another prime (21951229) 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, 10975764 + 10975765.

It is an arithmetic number, because the mean of its divisors is an integer number (10975765).

Almost surely, 2^21951529 is an apocalyptic number.

It is an amenable number.

21951529 is a deficient number, since it is larger than the sum of its proper divisors (1).

21951529 is an equidigital number, since it uses as much as digits as its factorization.

21951529 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 8100, while the sum is 34.

The square root of 21951529 is about 4685.2458846895. The cubic root of 21951529 is about 279.9979974347.

The spelling of 21951529 in words is "twenty-one million, nine hundred fifty-one thousand, five hundred twenty-nine".