20251540 has 24 divisors (see below), whose sum is σ = 43567272. Its totient is φ = 7902720.

The previous prime is 20251537. The next prime is 20251579. The reversal of 20251540 is 4515202.

It can be written as a sum of positive squares in 4 ways, for example, as 1898884 + 18352656 = 1378^2 + 4284^2 .

It is a congruent number.

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, 11529 + ... + 13168.

It is an arithmetic number, because the mean of its divisors is an integer number (1815303).

Almost surely, 2^20251540 is an apocalyptic number.

20251540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20251540 is an abundant number, since it is smaller than the sum of its proper divisors (23315732).

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

20251540 is a wasteful number, since it uses less digits than its factorization.

20251540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24747 (or 24745 counting only the distinct ones).

The product of its (nonzero) digits is 400, while the sum is 19.

The square root of 20251540 is about 4500.1711078580. The cubic root of 20251540 is about 272.5749982946.

Adding to 20251540 its reverse (4515202), we get a palindrome (24766742).

The spelling of 20251540 in words is "twenty million, two hundred fifty-one thousand, five hundred forty".