21850040 has 64 divisors (see below), whose sum is σ = 51701760. Its totient is φ = 8300160.

The previous prime is 21850039. The next prime is 21850043. The reversal of 21850040 is 4005812.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 21849994 and 21850021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21850043) 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, 82949 + ... + 83211.

It is an arithmetic number, because the mean of its divisors is an integer number (807840).

Almost surely, 2^21850040 is an apocalyptic number.

21850040 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 21850040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25850880).

21850040 is an abundant number, since it is smaller than the sum of its proper divisors (29851720).

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

21850040 is a wasteful number, since it uses less digits than its factorization.

21850040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 372 (or 368 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 20.

The square root of 21850040 is about 4674.4026356316. The cubic root of 21850040 is about 279.5658237000.

Adding to 21850040 its reverse (4005812), we get a palindrome (25855852).

The spelling of 21850040 in words is "twenty-one million, eight hundred fifty thousand, forty".