21001140 has 48 divisors (see below), whose sum is σ = 65338560. Its totient is φ = 5600160.

The previous prime is 21001121. The next prime is 21001153. The reversal of 21001140 is 4110012.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 18906 + ... + 19985.

It is an arithmetic number, because the mean of its divisors is an integer number (1361220).

Almost surely, 2^21001140 is an apocalyptic number.

21001140 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21001140 is an abundant number, since it is smaller than the sum of its proper divisors (44337420).

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

21001140 is a wasteful number, since it uses less digits than its factorization.

21001140 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38909 (or 38901 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 9.

The square root of 21001140 is about 4582.7000774652. The cubic root of 21001140 is about 275.8974098868.

Adding to 21001140 its reverse (4110012), we get a palindrome (25111152).

It can be divided in two parts, 2100 and 1140, that added together give a triangular number (3240 = T₈₀).

The spelling of 21001140 in words is "twenty-one million, one thousand, one hundred forty".