21247910 has 8 divisors (see below), whose sum is σ = 38246256. Its totient is φ = 8499160.

The previous prime is 21247873. The next prime is 21247913. The reversal of 21247910 is 1974212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21247910.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21247913) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1062386 + ... + 1062405.

It is an arithmetic number, because the mean of its divisors is an integer number (4780782).

Almost surely, 2^21247910 is an apocalyptic number.

21247910 is a deficient number, since it is larger than the sum of its proper divisors (16998346).

21247910 is a wasteful number, since it uses less digits than its factorization.

21247910 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2124798.

The product of its (nonzero) digits is 1008, while the sum is 26.

The square root of 21247910 is about 4609.5455307438. The cubic root of 21247910 is about 276.9738318453.

The spelling of 21247910 in words is "twenty-one million, two hundred forty-seven thousand, nine hundred ten".