40787721 has 24 divisors (see below), whose sum is σ = 64176840. Its totient is φ = 24811776.

The previous prime is 40787683. The next prime is 40787729. The reversal of 40787721 is 12778704.

Added to its reverse (12778704) it gives a triangular number (53566425 = T₁₀₃₅₀).

It can be written as a sum of positive squares in 4 ways, for example, as 1587600 + 39200121 = 1260^2 + 6261^2 .

It is not a de Polignac number, because 40787721 - 2¹⁸ = 40525577 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (40787729) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 8455 + ... + 12371.

It is an arithmetic number, because the mean of its divisors is an integer number (2674035).

Almost surely, 2^40787721 is an apocalyptic number.

It is an amenable number.

40787721 is a deficient number, since it is larger than the sum of its proper divisors (23389119).

40787721 is a wasteful number, since it uses less digits than its factorization.

40787721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4025 (or 4022 counting only the distinct ones).

The product of its (nonzero) digits is 21952, while the sum is 36.

The square root of 40787721 is about 6386.5265207310. The cubic root of 40787721 is about 344.2255849770.

Adding to 40787721 its reverse (12778704), we get a triangular number (53566425 = T₁₀₃₅₀).

The spelling of 40787721 in words is "forty million, seven hundred eighty-seven thousand, seven hundred twenty-one".