21372036 has 72 divisors (see below), whose sum is σ = 61094880. Its totient is φ = 5781888.

The previous prime is 21372031. The next prime is 21372041. The reversal of 21372036 is 63027312.

It is an interprime number because it is at equal distance from previous prime (21372031) and next prime (21372041).

It is a junction number, because it is equal to n+sod(n) for n = 21371997 and 21372015.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21372031) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 10216 + ... + 12128.

It is an arithmetic number, because the mean of its divisors is an integer number (848540).

Almost surely, 2^21372036 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 21372036, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30547440).

21372036 is an abundant number, since it is smaller than the sum of its proper divisors (39722844).

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

21372036 is a wasteful number, since it uses less digits than its factorization.

21372036 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1953 (or 1944 counting only the distinct ones).

The product of its (nonzero) digits is 1512, while the sum is 24.

The square root of 21372036 is about 4622.9899415854. The cubic root of 21372036 is about 277.5121267325.

Adding to 21372036 its reverse (63027312), we get a palindrome (84399348).

The spelling of 21372036 in words is "twenty-one million, three hundred seventy-two thousand, thirty-six".