20945640 has 64 divisors (see below), whose sum is σ = 65577600. Its totient is φ = 5341952.

The previous prime is 20945623. The next prime is 20945651. The reversal of 20945640 is 4654902.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 20945598 and 20945607.

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, 1035 + ... + 6554.

It is an arithmetic number, because the mean of its divisors is an integer number (1024650).

Almost surely, 2^20945640 is an apocalyptic number.

20945640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20945640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32788800).

20945640 is an abundant number, since it is smaller than the sum of its proper divisors (44631960).

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

20945640 is a wasteful number, since it uses less digits than its factorization.

20945640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7626 (or 7622 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 30.

The square root of 20945640 is about 4576.6406894140. The cubic root of 20945640 is about 275.6541561909.

The spelling of 20945640 in words is "twenty million, nine hundred forty-five thousand, six hundred forty".