21420944 has 10 divisors (see below), whose sum is σ = 41503110. Its totient is φ = 10710464.

The previous prime is 21420941. The next prime is 21420967. The reversal of 21420944 is 44902412.

It can be written as a sum of positive squares in only one way, i.e., 18490000 + 2930944 = 4300^2 + 1712^2 .

It is a super-2 number, since 2×21420944² = 917713683702272, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21420941) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 669389 + ... + 669420.

It is an arithmetic number, because the mean of its divisors is an integer number (4150311).

Almost surely, 2^21420944 is an apocalyptic number.

It is an amenable number.

21420944 is a deficient number, since it is larger than the sum of its proper divisors (20082166).

21420944 is a wasteful number, since it uses less digits than its factorization.

21420944 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1338817 (or 1338811 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 26.

The square root of 21420944 is about 4628.2765690914. The cubic root of 21420944 is about 277.7236527196.

The spelling of 21420944 in words is "twenty-one million, four hundred twenty thousand, nine hundred forty-four".