21372416 has 80 divisors (see below), whose sum is σ = 48694800. Its totient is φ = 9345024.

The previous prime is 21372413. The next prime is 21372427. The reversal of 21372416 is 61427312.

It is a Harshad number since it is a multiple of its sum of digits (26).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21372413) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1124855 + ... + 1124873.

It is an arithmetic number, because the mean of its divisors is an integer number (608685).

Almost surely, 2^21372416 is an apocalyptic number.

21372416 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21372416, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24347400).

21372416 is an abundant number, since it is smaller than the sum of its proper divisors (27322384).

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

21372416 is an frugal number, since it uses more digits than its factorization.

21372416 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 76 (or 34 counting only the distinct ones).

The product of its digits is 2016, while the sum is 26.

The square root of 21372416 is about 4623.0310403457. The cubic root of 21372416 is about 277.5137714671.

Adding to 21372416 its reverse (61427312), we get a palindrome (82799728).

The spelling of 21372416 in words is "twenty-one million, three hundred seventy-two thousand, four hundred sixteen".