21811948 has 24 divisors (see below), whose sum is σ = 39259584. Its totient is φ = 10598400.

The previous prime is 21811939. The next prime is 21811957. The reversal of 21811948 is 84911812.

It is an interprime number because it is at equal distance from previous prime (21811939) and next prime (21811957).

It is a super-2 number, since 2×21811948² = 951522151109408, which contains 22 as substring.

It is a hoax number, since the sum of its digits (34) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 33708 + ... + 34348.

It is an arithmetic number, because the mean of its divisors is an integer number (1635816).

Almost surely, 2^21811948 is an apocalyptic number.

It is an amenable number.

21811948 is a deficient number, since it is larger than the sum of its proper divisors (17447636).

21811948 is a wasteful number, since it uses less digits than its factorization.

21811948 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 873 (or 871 counting only the distinct ones).

The product of its digits is 4608, while the sum is 34.

The square root of 21811948 is about 4670.3263269283. The cubic root of 21811948 is about 279.4032699815.

The spelling of 21811948 in words is "twenty-one million, eight hundred eleven thousand, nine hundred forty-eight".