21273724 has 6 divisors (see below), whose sum is σ = 37229024. Its totient is φ = 10636860.

The previous prime is 21273713. The next prime is 21273737. The reversal of 21273724 is 42737212.

It is a junction number, because it is equal to n+sod(n) for n = 21273692 and 21273701.

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, 2659212 + ... + 2659219.

Almost surely, 2^21273724 is an apocalyptic number.

It is an amenable number.

21273724 is a deficient number, since it is larger than the sum of its proper divisors (15955300).

21273724 is a wasteful number, since it uses less digits than its factorization.

21273724 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5318435 (or 5318433 counting only the distinct ones).

The product of its digits is 4704, while the sum is 28.

The square root of 21273724 is about 4612.3447399343. The cubic root of 21273724 is about 277.0859512494.

The spelling of 21273724 in words is "twenty-one million, two hundred seventy-three thousand, seven hundred twenty-four".