8742239721 has 12 divisors (see below), whose sum is σ = 12649199472. Its totient is φ = 5818227576.

The previous prime is 8742239699. The next prime is 8742239761. The reversal of 8742239721 is 1279322478.

It is not a de Polignac number, because 8742239721 - 2¹⁴ = 8742223337 is a prime.

It is not an unprimeable number, because it can be changed into a prime (8742239761) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 822111 + ... + 832676.

It is an arithmetic number, because the mean of its divisors is an integer number (1054099956).

Almost surely, 2^8742239721 is an apocalyptic number.

It is an amenable number.

8742239721 is a deficient number, since it is larger than the sum of its proper divisors (3906959751).

8742239721 is a wasteful number, since it uses less digits than its factorization.

8742239721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1655380 (or 1655377 counting only the distinct ones).

The product of its digits is 338688, while the sum is 45.

The square root of 8742239721 is about 93499.9450320694. The cubic root of 8742239721 is about 2060.0332826024.

The spelling of 8742239721 in words is "eight billion, seven hundred forty-two million, two hundred thirty-nine thousand, seven hundred twenty-one".