21742086 has 8 divisors (see below), whose sum is σ = 43484184. Its totient is φ = 7247360.

The previous prime is 21742043. The next prime is 21742087. The reversal of 21742086 is 68024712.

It is a sphenic number, since it is the product of 3 distinct primes.

21742086 is an admirable number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21742087) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1811835 + ... + 1811846.

It is an arithmetic number, because the mean of its divisors is an integer number (5435523).

Almost surely, 2^21742086 is an apocalyptic number.

21742086 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

21742086 is a wasteful number, since it uses less digits than its factorization.

21742086 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3623686.

The product of its (nonzero) digits is 5376, while the sum is 30.

The square root of 21742086 is about 4662.8409794888. The cubic root of 21742086 is about 279.1046485040.

Adding to 21742086 its reverse (68024712), we get a palindrome (89766798).

The spelling of 21742086 in words is "twenty-one million, seven hundred forty-two thousand, eighty-six".