20724431 has 16 divisors (see below), whose sum is σ = 25994304. Its totient is φ = 16084224.

The previous prime is 20724427. The next prime is 20724437. The reversal of 20724431 is 13442702.

It is not a de Polignac number, because 20724431 - 2² = 20724427 is a prime.

It is a super-2 number, since 2×20724431² = 859004080547522, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 20724397 and 20724406.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20724437) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2675 + ... + 6971.

It is an arithmetic number, because the mean of its divisors is an integer number (1624644).

Almost surely, 2^20724431 is an apocalyptic number.

20724431 is a deficient number, since it is larger than the sum of its proper divisors (5269873).

20724431 is a wasteful number, since it uses less digits than its factorization.

20724431 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4370.

The product of its (nonzero) digits is 1344, while the sum is 23.

The square root of 20724431 is about 4552.4093620851. The cubic root of 20724431 is about 274.6803161190.

The spelling of 20724431 in words is "twenty million, seven hundred twenty-four thousand, four hundred thirty-one".