21485140 has 24 divisors (see below), whose sum is σ = 45972360. Its totient is φ = 8431488.

The previous prime is 21485129. The next prime is 21485147. The reversal of 21485140 is 4158412.

It can be written as a sum of positive squares in 4 ways, for example, as 6461764 + 15023376 = 2542^2 + 3876^2 .

It is a super-2 number, since 2×21485140² = 923222481639200, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21485147) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9075 + ... + 11194.

It is an arithmetic number, because the mean of its divisors is an integer number (1915515).

Almost surely, 2^21485140 is an apocalyptic number.

21485140 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21485140 is an abundant number, since it is smaller than the sum of its proper divisors (24487220).

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

21485140 is a wasteful number, since it uses less digits than its factorization.

21485140 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20331 (or 20329 counting only the distinct ones).

The product of its (nonzero) digits is 1280, while the sum is 25.

The square root of 21485140 is about 4635.2065757634. The cubic root of 21485140 is about 278.0008108597. Note that the first 3 decimals are identical.

The spelling of 21485140 in words is "twenty-one million, four hundred eighty-five thousand, one hundred forty".