20687490 has 48 divisors (see below), whose sum is σ = 54814968. Its totient is φ = 5411328.

The previous prime is 20687489. The next prime is 20687497. The reversal of 20687490 is 9478602.

It can be written as a sum of positive squares in 4 ways, for example, as 12341169 + 8346321 = 3513^2 + 2889^2 .

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (20687497) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2602 + ... + 6938.

Almost surely, 2^20687490 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20687490, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27407484).

20687490 is an abundant number, since it is smaller than the sum of its proper divisors (34127478).

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

20687490 is a wasteful number, since it uses less digits than its factorization.

20687490 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4403 (or 4400 counting only the distinct ones).

The product of its (nonzero) digits is 24192, while the sum is 36.

The square root of 20687490 is about 4548.3502503655. The cubic root of 20687490 is about 274.5170144828.

The spelling of 20687490 in words is "twenty million, six hundred eighty-seven thousand, four hundred ninety".