21421444 has 24 divisors (see below), whose sum is σ = 41025600. Its totient is φ = 9706080.

The previous prime is 21421427. The next prime is 21421451. The reversal of 21421444 is 44412412.

It is a Harshad number since it is a multiple of its sum of digits (22).

It is a nude number because it is divisible by every one of its digits.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18762 + ... + 19870.

It is an arithmetic number, because the mean of its divisors is an integer number (1709400).

Almost surely, 2^21421444 is an apocalyptic number.

It is an amenable number.

21421444 is a deficient number, since it is larger than the sum of its proper divisors (19604156).

21421444 is a wasteful number, since it uses less digits than its factorization.

21421444 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1563 (or 1561 counting only the distinct ones).

The product of its digits is 1024, while the sum is 22.

The square root of 21421444 is about 4628.3305845629. The cubic root of 21421444 is about 277.7258135448.

Adding to 21421444 its reverse (44412412), we get a palindrome (65833856).

The spelling of 21421444 in words is "twenty-one million, four hundred twenty-one thousand, four hundred forty-four".