21407228 has 6 divisors (see below), whose sum is σ = 37462656. Its totient is φ = 10703612.

The previous prime is 21407213. The next prime is 21407257. The reversal of 21407228 is 82270412.

It is a junction number, because it is equal to n+sod(n) for n = 21407197 and 21407206.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2675900 + ... + 2675907.

It is an arithmetic number, because the mean of its divisors is an integer number (6243776).

Almost surely, 2^21407228 is an apocalyptic number.

It is an amenable number.

21407228 is a deficient number, since it is larger than the sum of its proper divisors (16055428).

21407228 is a wasteful number, since it uses less digits than its factorization.

21407228 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5351811 (or 5351809 counting only the distinct ones).

The product of its (nonzero) digits is 1792, while the sum is 26.

The square root of 21407228 is about 4626.7945707585. The cubic root of 21407228 is about 277.6643638457.

The spelling of 21407228 in words is "twenty-one million, four hundred seven thousand, two hundred twenty-eight".