21251010 has 64 divisors (see below), whose sum is σ = 56484864. Its totient is φ = 5073600.

The previous prime is 21250979. The next prime is 21251017. The reversal of 21251010 is 1015212.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21251017) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 22977 + ... + 23883.

It is an arithmetic number, because the mean of its divisors is an integer number (882576).

Almost surely, 2^21251010 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21251010, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28242432).

21251010 is an abundant number, since it is smaller than the sum of its proper divisors (35233854).

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

21251010 is a wasteful number, since it uses less digits than its factorization.

21251010 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 999.

The product of its (nonzero) digits is 20, while the sum is 12.

The square root of 21251010 is about 4609.8817772260. The cubic root of 21251010 is about 276.9873010465.

Adding to 21251010 its reverse (1015212), we get a palindrome (22266222).

The spelling of 21251010 in words is "twenty-one million, two hundred fifty-one thousand, ten".