20723640 has 64 divisors (see below), whose sum is σ = 71055360. Its totient is φ = 4736640.

The previous prime is 20723639. The next prime is 20723669. The reversal of 20723640 is 4632702.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 20723640.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11496 + ... + 13175.

It is an arithmetic number, because the mean of its divisors is an integer number (1110240).

Almost surely, 2^20723640 is an apocalyptic number.

20723640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20723640 is an abundant number, since it is smaller than the sum of its proper divisors (50331720).

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

20723640 is a wasteful number, since it uses less digits than its factorization.

20723640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24692 (or 24688 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 24.

The square root of 20723640 is about 4552.3224841832. The cubic root of 20723640 is about 274.6768214530.

The spelling of 20723640 in words is "twenty million, seven hundred twenty-three thousand, six hundred forty".