20631440 has 20 divisors (see below), whose sum is σ = 47968284. Its totient is φ = 8252544.

The previous prime is 20631439. The next prime is 20631463. The reversal of 20631440 is 4413602.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 6130576 + 14500864 = 2476^2 + 3808^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a Harshad number since it is a multiple of its sum of digits (20).

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 128867 + ... + 129026.

Almost surely, 2^20631440 is an apocalyptic number.

20631440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20631440 is an abundant number, since it is smaller than the sum of its proper divisors (27336844).

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

20631440 is a wasteful number, since it uses less digits than its factorization.

20631440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 257906 (or 257900 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 20.

The square root of 20631440 is about 4542.1844964730. The cubic root of 20631440 is about 274.2688678063.

The spelling of 20631440 in words is "twenty million, six hundred thirty-one thousand, four hundred forty".