21415724 has 12 divisors (see below), whose sum is σ = 40884648. Its totient is φ = 9734400.

The previous prime is 21415721. The next prime is 21415727. The reversal of 21415724 is 42751412.

It is an interprime number because it is at equal distance from previous prime (21415721) and next prime (21415727).

It is a junction number, because it is equal to n+sod(n) for n = 21415693 and 21415702.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21415721) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 243317 + ... + 243404.

It is an arithmetic number, because the mean of its divisors is an integer number (3407054).

Almost surely, 2^21415724 is an apocalyptic number.

It is an amenable number.

21415724 is a deficient number, since it is larger than the sum of its proper divisors (19468924).

21415724 is a wasteful number, since it uses less digits than its factorization.

21415724 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 486736 (or 486734 counting only the distinct ones).

The product of its digits is 2240, while the sum is 26.

The square root of 21415724 is about 4627.7126099186. The cubic root of 21415724 is about 277.7010916964.

The spelling of 21415724 in words is "twenty-one million, four hundred fifteen thousand, seven hundred twenty-four".