21705148 has 12 divisors (see below), whose sum is σ = 38165512. Its totient is φ = 10800720.

The previous prime is 21705139. The next prime is 21705149. The reversal of 21705148 is 84150712.

It is a super-2 number, since 2×21705148² = 942226899403808, which contains 22 as substring.

It is a hoax number, since the sum of its digits (28) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21705149) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12015 + ... + 13702.

Almost surely, 2^21705148 is an apocalyptic number.

It is an amenable number.

21705148 is a deficient number, since it is larger than the sum of its proper divisors (16460364).

21705148 is a wasteful number, since it uses less digits than its factorization.

21705148 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25932 (or 25930 counting only the distinct ones).

The product of its (nonzero) digits is 2240, while the sum is 28.

The square root of 21705148 is about 4658.8784057968. The cubic root of 21705148 is about 278.9465003639.

The spelling of 21705148 in words is "twenty-one million, seven hundred five thousand, one hundred forty-eight".