21251870 has 32 divisors (see below), whose sum is σ = 40824000. Its totient is φ = 7937536.

The previous prime is 21251863. The next prime is 21251873. The reversal of 21251870 is 7815212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21251873) 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 15 ways as a sum of consecutive naturals, for example, 24911 + ... + 25749.

It is an arithmetic number, because the mean of its divisors is an integer number (1275750).

Almost surely, 2^21251870 is an apocalyptic number.

21251870 is a deficient number, since it is larger than the sum of its proper divisors (19572130).

21251870 is a wasteful number, since it uses less digits than its factorization.

21251870 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1012.

The product of its (nonzero) digits is 1120, while the sum is 26.

The square root of 21251870 is about 4609.9750541624. The cubic root of 21251870 is about 276.9910374315.

The spelling of 21251870 in words is "twenty-one million, two hundred fifty-one thousand, eight hundred seventy".