43720021787 has 4 divisors (see below), whose sum is σ = 47083100400. Its totient is φ = 40356943176.

The previous prime is 43720021783. The next prime is 43720021817. The reversal of 43720021787 is 78712002734.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 43720021787 - 2² = 43720021783 is a prime.

It is a super-2 number, since 2×43720021787² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (43720021781) 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, 1681539287 + ... + 1681539312.

It is an arithmetic number, because the mean of its divisors is an integer number (11770775100).

Almost surely, 2^43720021787 is an apocalyptic number.

43720021787 is a deficient number, since it is larger than the sum of its proper divisors (3363078613).

43720021787 is a wasteful number, since it uses less digits than its factorization.

43720021787 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3363078612.

The product of its (nonzero) digits is 131712, while the sum is 41.

The spelling of 43720021787 in words is "forty-three billion, seven hundred twenty million, twenty-one thousand, seven hundred eighty-seven".