40678921 has 2 divisors, whose sum is σ = 40678922. Its totient is φ = 40678920.

The previous prime is 40678919. The next prime is 40678961. The reversal of 40678921 is 12987604.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 33582025 + 7096896 = 5795^2 + 2664^2 .

It is a cyclic number.

It is not a de Polignac number, because 40678921 - 2¹ = 40678919 is a prime.

It is a super-3 number, since 3×40678921³ (a number of 24 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

Together with 40678919, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (40678961) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20339460 + 20339461.

It is an arithmetic number, because the mean of its divisors is an integer number (20339461).

Almost surely, 2^40678921 is an apocalyptic number.

It is an amenable number.

40678921 is a deficient number, since it is larger than the sum of its proper divisors (1).

40678921 is an equidigital number, since it uses as much as digits as its factorization.

40678921 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 24192, while the sum is 37.

The square root of 40678921 is about 6378.0029005951. The cubic root of 40678921 is about 343.9192420170.

Subtracting from 40678921 its sum of digits (37), we obtain a square (40678884 = 6378²).

The spelling of 40678921 in words is "forty million, six hundred seventy-eight thousand, nine hundred twenty-one".