21225511 has 2 divisors, whose sum is σ = 21225512. Its totient is φ = 21225510.

The previous prime is 21225487. The next prime is 21225541. The reversal of 21225511 is 11552212.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21225511 is a prime.

It is a super-2 number, since 2×21225511² = 901044634422242, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21225541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10612755 + 10612756.

It is an arithmetic number, because the mean of its divisors is an integer number (10612756).

Almost surely, 2^21225511 is an apocalyptic number.

21225511 is a deficient number, since it is larger than the sum of its proper divisors (1).

21225511 is an equidigital number, since it uses as much as digits as its factorization.

21225511 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 200, while the sum is 19.

The square root of 21225511 is about 4607.1152579461. The cubic root of 21225511 is about 276.8764713967.

Adding to 21225511 its reverse (11552212), we get a palindrome (32777723).

It can be divided in two parts, 21225 and 511, that added together give a triangular number (21736 = T₂₀₈).

The spelling of 21225511 in words is "twenty-one million, two hundred twenty-five thousand, five hundred eleven".