20400731 has 8 divisors (see below), whose sum is σ = 23262624. Its totient is φ = 17723520.

The previous prime is 20400719. The next prime is 20400803. The reversal of 20400731 is 13700402.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 20400731 - 2¹⁴ = 20384347 is a prime.

It is a super-2 number, since 2×20400731² = 832379650668722, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (17).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20400031) 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, 45935 + ... + 46376.

It is an arithmetic number, because the mean of its divisors is an integer number (2907828).

Almost surely, 2^20400731 is an apocalyptic number.

20400731 is a deficient number, since it is larger than the sum of its proper divisors (2861893).

20400731 is a wasteful number, since it uses less digits than its factorization.

20400731 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 92341.

The product of its (nonzero) digits is 168, while the sum is 17.

The square root of 20400731 is about 4516.7168385897. The cubic root of 20400731 is about 273.2427052638.

The spelling of 20400731 in words is "twenty million, four hundred thousand, seven hundred thirty-one".