21761740 has 96 divisors (see below), whose sum is σ = 61415424. Its totient is φ = 6255360.

The previous prime is 21761731. The next prime is 21761743. The reversal of 21761740 is 4716712.

It is a Harshad number since it is a multiple of its sum of digits (28).

It is a junction number, because it is equal to n+sod(n) for n = 21761699 and 21761708.

It is not an unprimeable number, because it can be changed into a prime (21761743) 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 31 ways as a sum of consecutive naturals, for example, 19477 + ... + 20563.

It is an arithmetic number, because the mean of its divisors is an integer number (639744).

Almost surely, 2^21761740 is an apocalyptic number.

21761740 is a gapful number since it is divisible by the number (20) 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 21761740, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30707712).

21761740 is an abundant number, since it is smaller than the sum of its proper divisors (39653684).

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

21761740 is a wasteful number, since it uses less digits than its factorization.

21761740 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1127 (or 1125 counting only the distinct ones).

The product of its (nonzero) digits is 2352, while the sum is 28.

The square root of 21761740 is about 4664.9480168594. The cubic root of 21761740 is about 279.1887230909.

It can be divided in two parts, 2176 and 1740, that added together give a triangular number (3916 = T₈₈).

The spelling of 21761740 in words is "twenty-one million, seven hundred sixty-one thousand, seven hundred forty".