21948021 has 12 divisors (see below), whose sum is σ = 33371520. Its totient is φ = 13861800.

The previous prime is 21947977. The next prime is 21948077. The reversal of 21948021 is 12084912.

It is not a de Polignac number, because 21948021 - 2¹³ = 21939829 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21948221) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 64005 + ... + 64346.

It is an arithmetic number, because the mean of its divisors is an integer number (2780960).

Almost surely, 2^21948021 is an apocalyptic number.

It is an amenable number.

21948021 is a deficient number, since it is larger than the sum of its proper divisors (11423499).

21948021 is a wasteful number, since it uses less digits than its factorization.

21948021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128376 (or 128373 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 27.

The square root of 21948021 is about 4684.8715030404. The cubic root of 21948021 is about 279.9830814607.

The spelling of 21948021 in words is "twenty-one million, nine hundred forty-eight thousand, twenty-one".