20987240 has 16 divisors (see below), whose sum is σ = 47221380. Its totient is φ = 8394880.

The previous prime is 20987237. The next prime is 20987243. The reversal of 20987240 is 4278902.

It is an interprime number because it is at equal distance from previous prime (20987237) and next prime (20987243).

It can be written as a sum of positive squares in 2 ways, for example, as 20448484 + 538756 = 4522^2 + 734^2 .

It is a junction number, because it is equal to n+sod(n) for n = 20987197 and 20987206.

It is not an unprimeable number, because it can be changed into a prime (20987243) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 262301 + ... + 262380.

Almost surely, 2^20987240 is an apocalyptic number.

20987240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20987240 is an abundant number, since it is smaller than the sum of its proper divisors (26234140).

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

20987240 is a wasteful number, since it uses less digits than its factorization.

20987240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 524692 (or 524688 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 32.

The square root of 20987240 is about 4581.1832532655. The cubic root of 20987240 is about 275.8365271539.

The spelling of 20987240 in words is "twenty million, nine hundred eighty-seven thousand, two hundred forty".