20783440 has 40 divisors (see below), whose sum is σ = 48568320. Its totient is φ = 8270976.

The previous prime is 20783437. The next prime is 20783479. The reversal of 20783440 is 4438702.

It is a tau number, because it is divible by the number of its divisors (40).

It is a junction number, because it is equal to n+sod(n) for n = 20783399 and 20783408.

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, 18577 + ... + 19663.

It is an arithmetic number, because the mean of its divisors is an integer number (1214208).

Almost surely, 2^20783440 is an apocalyptic number.

20783440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20783440 is an abundant number, since it is smaller than the sum of its proper divisors (27784880).

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

20783440 is a wasteful number, since it uses less digits than its factorization.

20783440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1339 (or 1333 counting only the distinct ones).

The product of its (nonzero) digits is 5376, while the sum is 28.

The square root of 20783440 is about 4558.8858287963. The cubic root of 20783440 is about 274.9407696128.

The spelling of 20783440 in words is "twenty million, seven hundred eighty-three thousand, four hundred forty".