21951265 has 12 divisors (see below), whose sum is σ = 30642516. Its totient is φ = 15052128.

The previous prime is 21951263. The next prime is 21951329. The reversal of 21951265 is 56215912.

It can be written as a sum of positive squares in 2 ways, for example, as 16711744 + 5239521 = 4088^2 + 2289^2 .

It is not a de Polignac number, because 21951265 - 2¹ = 21951263 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21951263) 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 in 11 ways as a sum of consecutive naturals, for example, 44554 + ... + 45043.

It is an arithmetic number, because the mean of its divisors is an integer number (2553543).

Almost surely, 2^21951265 is an apocalyptic number.

It is an amenable number.

21951265 is a deficient number, since it is larger than the sum of its proper divisors (8691251).

21951265 is an equidigital number, since it uses as much as digits as its factorization.

21951265 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 89616 (or 89609 counting only the distinct ones).

The product of its digits is 5400, while the sum is 31.

The square root of 21951265 is about 4685.2177110568. The cubic root of 21951265 is about 279.9968749651.

The spelling of 21951265 in words is "twenty-one million, nine hundred fifty-one thousand, two hundred sixty-five".