21287948 has 24 divisors (see below), whose sum is σ = 41954304. Its totient is φ = 9363600.

The previous prime is 21287921. The next prime is 21287951. The reversal of 21287948 is 84978212.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6440 + ... + 9167.

It is an arithmetic number, because the mean of its divisors is an integer number (1748096).

Almost surely, 2^21287948 is an apocalyptic number.

It is an amenable number.

21287948 is a deficient number, since it is larger than the sum of its proper divisors (20666356).

21287948 is a wasteful number, since it uses less digits than its factorization.

21287948 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15653 (or 15651 counting only the distinct ones).

The product of its digits is 64512, while the sum is 41.

The square root of 21287948 is about 4613.8864311988. The cubic root of 21287948 is about 277.1476923985.

The spelling of 21287948 in words is "twenty-one million, two hundred eighty-seven thousand, nine hundred forty-eight".