20405724 has 12 divisors (see below), whose sum is σ = 47613384. Its totient is φ = 6801904.

The previous prime is 20405713. The next prime is 20405743. The reversal of 20405724 is 42750402.

It is a tau number, because it is divible by the number of its divisors (12).

It is a junction number, because it is equal to n+sod(n) for n = 20405694 and 20405703.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 850227 + ... + 850250.

It is an arithmetic number, because the mean of its divisors is an integer number (3967782).

Almost surely, 2^20405724 is an apocalyptic number.

It is an amenable number.

20405724 is an abundant number, since it is smaller than the sum of its proper divisors (27207660).

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

20405724 is a wasteful number, since it uses less digits than its factorization.

20405724 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1700484 (or 1700482 counting only the distinct ones).

The product of its (nonzero) digits is 2240, while the sum is 24.

The square root of 20405724 is about 4517.2695292621. The cubic root of 20405724 is about 273.2649951438.

The spelling of 20405724 in words is "twenty million, four hundred five thousand, seven hundred twenty-four".