40206721 has 16 divisors (see below), whose sum is σ = 42718720. Its totient is φ = 37791360.

The previous prime is 40206709. The next prime is 40206811. The reversal of 40206721 is 12760204.

It is a 10-Lehmer number, since φ(40206721) divides (40206721-1)¹⁰.

It is a cyclic number.

It is not a de Polignac number, because 40206721 - 2¹⁵ = 40173953 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 40206692 and 40206701.

It is not an unprimeable number, because it can be changed into a prime (40206121) 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, 246586 + ... + 246748.

It is an arithmetic number, because the mean of its divisors is an integer number (2669920).

Almost surely, 2^40206721 is an apocalyptic number.

It is an amenable number.

40206721 is a deficient number, since it is larger than the sum of its proper divisors (2511999).

40206721 is a wasteful number, since it uses less digits than its factorization.

40206721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 376.

The product of its (nonzero) digits is 672, while the sum is 22.

The square root of 40206721 is about 6340.8769898177. The cubic root of 40206721 is about 342.5833238940.

Adding to 40206721 its reverse (12760204), we get a palindrome (52966925).

The spelling of 40206721 in words is "forty million, two hundred six thousand, seven hundred twenty-one".