1985682721 has 9 divisors (see below), whose sum is σ = 2183148849. Its totient is φ = 1804720500.

The previous prime is 1985682703. The next prime is 1985682733. The reversal of 1985682721 is 1272865891.

It is a happy number.

The square root of 1985682721 is 44561.

It is a perfect power (a square), and thus also a powerful number.

It is not a de Polignac number, because 1985682721 - 2¹⁹ = 1985158433 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1985682791) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 488146 + ... + 492196.

Almost surely, 2^1985682721 is an apocalyptic number.

1985682721 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

1985682721 is the 44561-st square number.

1985682721 is the 22281-st centered octagonal number.

It is an amenable number.

1985682721 is a deficient number, since it is larger than the sum of its proper divisors (197466128).

1985682721 is an frugal number, since it uses more digits than its factorization.

1985682721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8124 (or 4062 counting only the distinct ones).

The product of its digits is 483840, while the sum is 49.

The cubic root of 1985682721 is about 1256.9074070214.

Multiplying 1985682721 by its sum of digits (49), we get a square (97298453329 = 311927²).

The spelling of 1985682721 in words is "one billion, nine hundred eighty-five million, six hundred eighty-two thousand, seven hundred twenty-one".