21253495 has 32 divisors (see below), whose sum is σ = 28615680. Its totient is φ = 15079680.

The previous prime is 21253493. The next prime is 21253499. The reversal of 21253495 is 59435212.

It is not a de Polignac number, because 21253495 - 2¹ = 21253493 is a prime.

It is a super-2 number, since 2×21253495² = 903422099430050, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21253493) 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 31 ways as a sum of consecutive naturals, for example, 155067 + ... + 155203.

It is an arithmetic number, because the mean of its divisors is an integer number (894240).

Almost surely, 2^21253495 is an apocalyptic number.

21253495 is a deficient number, since it is larger than the sum of its proper divisors (7362185).

21253495 is a wasteful number, since it uses less digits than its factorization.

21253495 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 255.

The product of its digits is 10800, while the sum is 31.

The square root of 21253495 is about 4610.1512990356. The cubic root of 21253495 is about 276.9980971862.

The spelling of 21253495 in words is "twenty-one million, two hundred fifty-three thousand, four hundred ninety-five".