21677742 has 48 divisors (see below), whose sum is σ = 49465728. Its totient is φ = 6851520.

The previous prime is 21677741. The next prime is 21677779. The reversal of 21677742 is 24777612.

It is a happy number.

It is a plaindrome in base 11.

It is a junction number, because it is equal to n+sod(n) for n = 21677697 and 21677706.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21677741) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 29208 + ... + 29940.

It is an arithmetic number, because the mean of its divisors is an integer number (1030536).

Almost surely, 2^21677742 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21677742, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24732864).

21677742 is an abundant number, since it is smaller than the sum of its proper divisors (27787986).

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

21677742 is a wasteful number, since it uses less digits than its factorization.

21677742 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 825 (or 822 counting only the distinct ones).

The product of its digits is 32928, while the sum is 36.

The square root of 21677742 is about 4655.9362109032. The cubic root of 21677742 is about 278.8290470049.

The spelling of 21677742 in words is "twenty-one million, six hundred seventy-seven thousand, seven hundred forty-two".