21749416 has 32 divisors (see below), whose sum is σ = 44220960. Its totient is φ = 9968832.

The previous prime is 21749353. The next prime is 21749419. The reversal of 21749416 is 61494712.

It is a Smith number, since the sum of its digits (34) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21749419) 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, 16311 + ... + 17593.

It is an arithmetic number, because the mean of its divisors is an integer number (1381905).

Almost surely, 2^21749416 is an apocalyptic number.

21749416 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 21749416, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22110480).

21749416 is an abundant number, since it is smaller than the sum of its proper divisors (22471544).

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

21749416 is a wasteful number, since it uses less digits than its factorization.

21749416 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1465 (or 1461 counting only the distinct ones).

The product of its digits is 12096, while the sum is 34.

The square root of 21749416 is about 4663.6269147521. The cubic root of 21749416 is about 279.1360102174.

The spelling of 21749416 in words is "twenty-one million, seven hundred forty-nine thousand, four hundred sixteen".