40021789 has 2 divisors, whose sum is σ = 40021790. Its totient is φ = 40021788.

The previous prime is 40021763. The next prime is 40021819. The reversal of 40021789 is 98712004.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 37822500 + 2199289 = 6150^2 + 1483^2 .

It is a cyclic number.

It is not a de Polignac number, because 40021789 - 2⁷ = 40021661 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 40021789.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (40021759) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20010894 + 20010895.

It is an arithmetic number, because the mean of its divisors is an integer number (20010895).

Almost surely, 2^40021789 is an apocalyptic number.

It is an amenable number.

40021789 is a deficient number, since it is larger than the sum of its proper divisors (1).

40021789 is an equidigital number, since it uses as much as digits as its factorization.

40021789 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4032, while the sum is 31.

The square root of 40021789 is about 6326.2776575171. The cubic root of 40021789 is about 342.0572758399.

The spelling of 40021789 in words is "forty million, twenty-one thousand, seven hundred eighty-nine".