40685921 has 2 divisors, whose sum is σ = 40685922. Its totient is φ = 40685920.

The previous prime is 40685881. The next prime is 40685923. The reversal of 40685921 is 12958604.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 37075921 + 3610000 = 6089^2 + 1900^2 .

It is a cyclic number.

It is not a de Polignac number, because 40685921 - 2¹⁴ = 40669537 is a prime.

Together with 40685923, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (40685923) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20342960 + 20342961.

It is an arithmetic number, because the mean of its divisors is an integer number (20342961).

Almost surely, 2^40685921 is an apocalyptic number.

It is an amenable number.

40685921 is a deficient number, since it is larger than the sum of its proper divisors (1).

40685921 is an equidigital number, since it uses as much as digits as its factorization.

40685921 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 17280, while the sum is 35.

The square root of 40685921 is about 6378.5516381072. The cubic root of 40685921 is about 343.9389680123.

The spelling of 40685921 in words is "forty million, six hundred eighty-five thousand, nine hundred twenty-one".