21048721 has 8 divisors (see below), whose sum is σ = 22085888. Its totient is φ = 20034000.

The previous prime is 21048707. The next prime is 21048757. The reversal of 21048721 is 12784012.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 21048721 - 2⁷ = 21048593 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21048701) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3675 + ... + 7456.

It is an arithmetic number, because the mean of its divisors is an integer number (2760736).

Almost surely, 2^21048721 is an apocalyptic number.

It is an amenable number.

21048721 is a deficient number, since it is larger than the sum of its proper divisors (1037167).

21048721 is a wasteful number, since it uses less digits than its factorization.

21048721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11223.

The product of its (nonzero) digits is 896, while the sum is 25.

The square root of 21048721 is about 4587.8885121589. Note that the first 3 decimals coincide. The cubic root of 21048721 is about 276.1056140300.

The spelling of 21048721 in words is "twenty-one million, forty-eight thousand, seven hundred twenty-one".