4390786021 has 4 divisors (see below), whose sum is σ = 4422835692. Its totient is φ = 4358736352.

The previous prime is 4390785941. The next prime is 4390786033. The reversal of 4390786021 is 1206870934.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1206870934 = 2 ⋅603435467.

It can be written as a sum of positive squares in 2 ways, for example, as 2799573921 + 1591212100 = 52911^2 + 39890^2 .

It is a cyclic number.

It is not a de Polignac number, because 4390786021 - 2¹³ = 4390777829 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (4390786051) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16024630 + ... + 16024903.

It is an arithmetic number, because the mean of its divisors is an integer number (1105708923).

Almost surely, 2^4390786021 is an apocalyptic number.

It is an amenable number.

4390786021 is a deficient number, since it is larger than the sum of its proper divisors (32049671).

4390786021 is a wasteful number, since it uses less digits than its factorization.

4390786021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32049670.

The product of its (nonzero) digits is 72576, while the sum is 40.

The square root of 4390786021 is about 66263.0064289268. The cubic root of 4390786021 is about 1637.4979223096.

The spelling of 4390786021 in words is "four billion, three hundred ninety million, seven hundred eighty-six thousand, twenty-one".