21723948 has 18 divisors (see below), whose sum is σ = 54913404. Its totient is φ = 7241304.

The previous prime is 21723931. The next prime is 21723959. The reversal of 21723948 is 84932712.

It is a tau number, because it is divible by the number of its divisors (18).

It is a Harshad number since it is a multiple of its sum of digits (36), and also a Moran number because the ratio is a prime number: 603443 = 21723948 / (2 + 1 + 7 + 2 + 3 + 9 + 4 + 8).

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 301686 + ... + 301757.

Almost surely, 2^21723948 is an apocalyptic number.

It is an amenable number.

21723948 is an abundant number, since it is smaller than the sum of its proper divisors (33189456).

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

21723948 is a wasteful number, since it uses less digits than its factorization.

21723948 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 603453 (or 603448 counting only the distinct ones).

The product of its digits is 24192, while the sum is 36.

The square root of 21723948 is about 4660.8956220881. The cubic root of 21723948 is about 279.0270139951.

The spelling of 21723948 in words is "twenty-one million, seven hundred twenty-three thousand, nine hundred forty-eight".