21601724 has 12 divisors (see below), whose sum is σ = 38228400. Its totient is φ = 10679328.

The previous prime is 21601721. The next prime is 21601757. The reversal of 21601724 is 42710612.

It is a self number, because there is not a number n which added to its sum of digits gives 21601724.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21601721) 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, 29984 + ... + 30695.

It is an arithmetic number, because the mean of its divisors is an integer number (3185700).

Almost surely, 2^21601724 is an apocalyptic number.

It is an amenable number.

21601724 is a deficient number, since it is larger than the sum of its proper divisors (16626676).

21601724 is a wasteful number, since it uses less digits than its factorization.

21601724 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 60772 (or 60770 counting only the distinct ones).

The product of its (nonzero) digits is 672, while the sum is 23.

The square root of 21601724 is about 4647.7654846173. The cubic root of 21601724 is about 278.5027391707.

The spelling of 21601724 in words is "twenty-one million, six hundred one thousand, seven hundred twenty-four".