249561192721 has 9 divisors (see below), whose sum is σ = 250277111721. Its totient is φ = 248847320052.

The previous prime is 249561192641. The next prime is 249561192733. The reversal of 249561192721 is 127291165942.

The square root of 249561192721 is 499561.

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

It is not a de Polignac number, because 249561192721 - 2⁷ = 249561192593 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (249561195721) 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, 303233116 + ... + 303233938.

It is an arithmetic number, because the mean of its divisors is an integer number (27808567969).

Almost surely, 2^249561192721 is an apocalyptic number.

249561192721 is the 499561-st square number.

249561192721 is the 249781-st centered octagonal number.

It is an amenable number.

249561192721 is a deficient number, since it is larger than the sum of its proper divisors (715919000).

249561192721 is an frugal number, since it uses more digits than its factorization.

249561192721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2860 (or 1430 counting only the distinct ones).

The product of its digits is 544320, while the sum is 49.

Multiplying 249561192721 by its sum of digits (49), we get a square (12228498443329 = 3496927²).

The spelling of 249561192721 in words is "two hundred forty-nine billion, five hundred sixty-one million, one hundred ninety-two thousand, seven hundred twenty-one".