20939780 has 24 divisors (see below), whose sum is σ = 45163608. Its totient is φ = 8149248.

The previous prime is 20939771. The next prime is 20939783. The reversal of 20939780 is 8793902.

It can be written as a sum of positive squares in 4 ways, for example, as 1982464 + 18957316 = 1408^2 + 4354^2 .

It is not an unprimeable number, because it can be changed into a prime (20939783) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13409 + ... + 14888.

It is an arithmetic number, because the mean of its divisors is an integer number (1881817).

Almost surely, 2^20939780 is an apocalyptic number.

20939780 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20939780 is an abundant number, since it is smaller than the sum of its proper divisors (24223828).

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

20939780 is a wasteful number, since it uses less digits than its factorization.

20939780 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28343 (or 28341 counting only the distinct ones).

The product of its (nonzero) digits is 27216, while the sum is 38.

The square root of 20939780 is about 4576.0004370629. Note that the first 3 decimals coincide. The cubic root of 20939780 is about 275.6284470374.

The spelling of 20939780 in words is "twenty million, nine hundred thirty-nine thousand, seven hundred eighty".