21662040 has 64 divisors (see below), whose sum is σ = 65691360. Its totient is φ = 5713920.

The previous prime is 21661999. The next prime is 21662041. The reversal of 21662040 is 4026612.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21661998 and 21662016.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21662041) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10710 + ... + 12570.

Almost surely, 2^21662040 is an apocalyptic number.

21662040 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 21662040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32845680).

21662040 is an abundant number, since it is smaller than the sum of its proper divisors (44029320).

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

21662040 is a wasteful number, since it uses less digits than its factorization.

21662040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1972 (or 1968 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 21.

The square root of 21662040 is about 4654.2496709996. The cubic root of 21662040 is about 278.7617086383.

Adding to 21662040 its reverse (4026612), we get a palindrome (25688652).

The spelling of 21662040 in words is "twenty-one million, six hundred sixty-two thousand, forty".