21235140 has 36 divisors (see below), whose sum is σ = 64413804. Its totient is φ = 5662656.

The previous prime is 21235127. The next prime is 21235147. The reversal of 21235140 is 4153212.

It can be written as a sum of positive squares in 2 ways, for example, as 16064064 + 5171076 = 4008^2 + 2274^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is not an unprimeable number, because it can be changed into a prime (21235147) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 58807 + ... + 59166.

Almost surely, 2^21235140 is an apocalyptic number.

21235140 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21235140 is an abundant number, since it is smaller than the sum of its proper divisors (43178664).

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

21235140 is a wasteful number, since it uses less digits than its factorization.

21235140 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 117988 (or 117983 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 21235140 is about 4608.1601534669. The cubic root of 21235140 is about 276.9183336082.

Adding to 21235140 its reverse (4153212), we get a palindrome (25388352).

The spelling of 21235140 in words is "twenty-one million, two hundred thirty-five thousand, one hundred forty".