1985147721 has 24 divisors (see below), whose sum is σ = 3037619520. Its totient is φ = 1245774816.

The previous prime is 1985147719. The next prime is 1985147741. The reversal of 1985147721 is 1277415891.

It is a happy number.

It is not a de Polignac number, because 1985147721 - 2¹ = 1985147719 is a prime.

It is a super-2 number, since 2×1985147721² = 7881622948382987682, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1985147741) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 10125 + ... + 63818.

It is an arithmetic number, because the mean of its divisors is an integer number (126567480).

Almost surely, 2^1985147721 is an apocalyptic number.

It is an amenable number.

1985147721 is a deficient number, since it is larger than the sum of its proper divisors (1052471799).

1985147721 is a wasteful number, since it uses less digits than its factorization.

1985147721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 74125 (or 74122 counting only the distinct ones).

The product of its digits is 141120, while the sum is 45.

The square root of 1985147721 is about 44554.9965884860. The cubic root of 1985147721 is about 1256.7945145543.

The spelling of 1985147721 in words is "one billion, nine hundred eighty-five million, one hundred forty-seven thousand, seven hundred twenty-one".