21870120 has 64 divisors (see below), whose sum is σ = 66744000. Its totient is φ = 5731328.

The previous prime is 21870103. The next prime is 21870127. The reversal of 21870120 is 2107812.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21870127) 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, 5536 + ... + 8624.

It is an arithmetic number, because the mean of its divisors is an integer number (1042875).

Almost surely, 2^21870120 is an apocalyptic number.

21870120 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 21870120, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33372000).

21870120 is an abundant number, since it is smaller than the sum of its proper divisors (44873880).

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

21870120 is a wasteful number, since it uses less digits than its factorization.

21870120 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3162 (or 3158 counting only the distinct ones).

The product of its (nonzero) digits is 224, while the sum is 21.

The square root of 21870120 is about 4676.5500104244. The cubic root of 21870120 is about 279.6514370135.

Adding to 21870120 its reverse (2107812), we get a palindrome (23977932).

It can be divided in two parts, 21870 and 120, that multiplied together give a square (2624400 = 1620²).

The spelling of 21870120 in words is "twenty-one million, eight hundred seventy thousand, one hundred twenty".