21145040 has 80 divisors (see below), whose sum is σ = 57198720. Its totient is φ = 7119360.

The previous prime is 21145001. The next prime is 21145049. The reversal of 21145040 is 4054112.

It is a tau number, because it is divible by the number of its divisors (80).

It is a super-2 number, since 2×21145040² = 894225433203200, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21145049) 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, 33851 + ... + 34469.

It is an arithmetic number, because the mean of its divisors is an integer number (714984).

Almost surely, 2^21145040 is an apocalyptic number.

21145040 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 21145040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28599360).

21145040 is an abundant number, since it is smaller than the sum of its proper divisors (36053680).

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

21145040 is a wasteful number, since it uses less digits than its factorization.

21145040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 700 (or 694 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 17.

The square root of 21145040 is about 4598.3736255333. The cubic root of 21145040 is about 276.5261265856.

Adding to 21145040 its reverse (4054112), we get a palindrome (25199152).

The spelling of 21145040 in words is "twenty-one million, one hundred forty-five thousand, forty".