21961716 has 48 divisors (see below), whose sum is σ = 59681664. Its totient is φ = 6155136.

The previous prime is 21961697. The next prime is 21961721. The reversal of 21961716 is 61716912.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1986 + ... + 6918.

It is an arithmetic number, because the mean of its divisors is an integer number (1243368).

Almost surely, 2^21961716 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 21961716, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29840832).

21961716 is an abundant number, since it is smaller than the sum of its proper divisors (37719948).

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

21961716 is a wasteful number, since it uses less digits than its factorization.

21961716 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5000 (or 4998 counting only the distinct ones).

The product of its digits is 4536, while the sum is 33.

The square root of 21961716 is about 4686.3328947056. The cubic root of 21961716 is about 280.0413034307.

It can be divided in two parts, 21 and 961716, that multiplied together give a square (20196036 = 4494²).

The spelling of 21961716 in words is "twenty-one million, nine hundred sixty-one thousand, seven hundred sixteen".