21948881 has 4 divisors (see below), whose sum is σ = 22542132. Its totient is φ = 21355632.

The previous prime is 21948863. The next prime is 21948893. The reversal of 21948881 is 18884912.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 19360000 + 2588881 = 4400^2 + 1609^2 .

It is a cyclic number.

It is not a de Polignac number, because 21948881 - 2¹⁰ = 21947857 is a prime.

It is a super-2 number, since 2×21948881² = 963506754304322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21948811) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 296570 + ... + 296643.

It is an arithmetic number, because the mean of its divisors is an integer number (5635533).

Almost surely, 2^21948881 is an apocalyptic number.

It is an amenable number.

21948881 is a deficient number, since it is larger than the sum of its proper divisors (593251).

21948881 is an equidigital number, since it uses as much as digits as its factorization.

21948881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 593250.

The product of its digits is 36864, while the sum is 41.

The square root of 21948881 is about 4684.9632869426. The cubic root of 21948881 is about 279.9867383175.

The spelling of 21948881 in words is "twenty-one million, nine hundred forty-eight thousand, eight hundred eighty-one".