842721509 has 16 divisors (see below), whose sum is σ = 1000281600. Its totient is φ = 694894464.

The previous prime is 842721479. The next prime is 842721557. The reversal of 842721509 is 905127248.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-842721509 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (842781509) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4772 + ... + 41330.

It is an arithmetic number, because the mean of its divisors is an integer number (62517600).

Almost surely, 2^842721509 is an apocalyptic number.

842721509 is a gapful number since it is divisible by the number (89) formed by its first and last digit.

It is an amenable number.

842721509 is a deficient number, since it is larger than the sum of its proper divisors (157560091).

842721509 is a wasteful number, since it uses less digits than its factorization.

842721509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36692.

The product of its (nonzero) digits is 40320, while the sum is 38.

The square root of 842721509 is about 29029.6660159913. Note that the first 3 decimals coincide. The cubic root of 842721509 is about 944.5566853973.

The spelling of 842721509 in words is "eight hundred forty-two million, seven hundred twenty-one thousand, five hundred nine".