21373428 has 12 divisors (see below), whose sum is σ = 49871360. Its totient is φ = 7124472.

The previous prime is 21373411. The next prime is 21373447. The reversal of 21373428 is 82437312.

It is a tau number, because it is divible by the number of its divisors (12).

It is a junction number, because it is equal to n+sod(n) for n = 21373395 and 21373404.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 890548 + ... + 890571.

Almost surely, 2^21373428 is an apocalyptic number.

It is an amenable number.

21373428 is an abundant number, since it is smaller than the sum of its proper divisors (28497932).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21373428 is a wasteful number, since it uses less digits than its factorization.

21373428 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1781126 (or 1781124 counting only the distinct ones).

The product of its digits is 8064, while the sum is 30.

The square root of 21373428 is about 4623.1404910515. The cubic root of 21373428 is about 277.5181515600.

It can be divided in two parts, 2137 and 3428, that added together give a triangular number (5565 = T₁₀₅).

The spelling of 21373428 in words is "twenty-one million, three hundred seventy-three thousand, four hundred twenty-eight".