20781534 has 16 divisors (see below), whose sum is σ = 41727888. Its totient is φ = 6899712.

The previous prime is 20781533. The next prime is 20781557. The reversal of 20781534 is 43518702.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20781533) 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, 5197 + ... + 8280.

It is an arithmetic number, because the mean of its divisors is an integer number (2607993).

Almost surely, 2^20781534 is an apocalyptic number.

20781534 is an abundant number, since it is smaller than the sum of its proper divisors (20946354).

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

20781534 is a wasteful number, since it uses less digits than its factorization.

20781534 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13739.

The product of its (nonzero) digits is 6720, while the sum is 30.

The square root of 20781534 is about 4558.6767816988. The cubic root of 20781534 is about 274.9323646339.

The spelling of 20781534 in words is "twenty million, seven hundred eighty-one thousand, five hundred thirty-four".