20720161 has 24 divisors (see below), whose sum is σ = 27578880. Its totient is φ = 15185280.

The previous prime is 20720153. The next prime is 20720209. The reversal of 20720161 is 16102702.

It is not a de Polignac number, because 20720161 - 2³ = 20720153 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20720131) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 13680 + ... + 15118.

It is an arithmetic number, because the mean of its divisors is an integer number (1149120).

Almost surely, 2^20720161 is an apocalyptic number.

It is an amenable number.

20720161 is a deficient number, since it is larger than the sum of its proper divisors (6858719).

20720161 is a wasteful number, since it uses less digits than its factorization.

20720161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1485 (or 1474 counting only the distinct ones).

The product of its (nonzero) digits is 168, while the sum is 19.

The square root of 20720161 is about 4551.9403554968. The cubic root of 20720161 is about 274.6614500520.

Adding to 20720161 its reverse (16102702), we get a palindrome (36822863).

The spelling of 20720161 in words is "twenty million, seven hundred twenty thousand, one hundred sixty-one".