21615672 has 64 divisors (see below), whose sum is σ = 60228000. Its totient is φ = 6418944.

The previous prime is 21615667. The next prime is 21615677. The reversal of 21615672 is 27651612.

It is an interprime number because it is at equal distance from previous prime (21615667) and next prime (21615677).

It is a super-3 number, since 3×21615672³ (a number of 23 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21615677) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 7854 + ... + 10242.

Almost surely, 2^21615672 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21615672, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30114000).

21615672 is an abundant number, since it is smaller than the sum of its proper divisors (38612328).

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

21615672 is a wasteful number, since it uses less digits than its factorization.

21615672 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2440 (or 2436 counting only the distinct ones).

The product of its digits is 5040, while the sum is 30.

The square root of 21615672 is about 4649.2657484812. The cubic root of 21615672 is about 278.5626683448.

The spelling of 21615672 in words is "twenty-one million, six hundred fifteen thousand, six hundred seventy-two".