21253910 has 64 divisors (see below), whose sum is σ = 43338240. Its totient is φ = 7464960.

The previous prime is 21253891. The next prime is 21253919. The reversal of 21253910 is 1935212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21253919) 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 in 31 ways as a sum of consecutive naturals, for example, 194936 + ... + 195044.

It is an arithmetic number, because the mean of its divisors is an integer number (677160).

Almost surely, 2^21253910 is an apocalyptic number.

21253910 is an abundant number, since it is smaller than the sum of its proper divisors (22084330).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21253910 is a wasteful number, since it uses less digits than its factorization.

21253910 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 201.

The product of its (nonzero) digits is 540, while the sum is 23.

The square root of 21253910 is about 4610.1963081847. The cubic root of 21253910 is about 276.9999000812. Note that the first 4 decimals are identical.

Adding to 21253910 its sum of digits (23), we get a cube (21253933 = 277³).

The spelling of 21253910 in words is "twenty-one million, two hundred fifty-three thousand, nine hundred ten".