21451040 has 48 divisors (see below), whose sum is σ = 54581688. Its totient is φ = 7919616.

The previous prime is 21451033. The next prime is 21451063. The reversal of 21451040 is 4015412.

It can be written as a sum of positive squares in 4 ways, for example, as 12475024 + 8976016 = 3532^2 + 2996^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3077 + ... + 7236.

Almost surely, 2^21451040 is an apocalyptic number.

21451040 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21451040 is an abundant number, since it is smaller than the sum of its proper divisors (33130648).

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

21451040 is a wasteful number, since it uses less digits than its factorization.

21451040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10341 (or 10333 counting only the distinct ones).

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

The square root of 21451040 is about 4631.5267461173. The cubic root of 21451040 is about 277.8536572556.

Adding to 21451040 its reverse (4015412), we get a palindrome (25466452).

The spelling of 21451040 in words is "twenty-one million, four hundred fifty-one thousand, forty".