780891221 has 16 divisors (see below), whose sum is σ = 865305600. Its totient is φ = 698770800.

The previous prime is 780891211. The next prime is 780891227. The reversal of 780891221 is 122198087.

It is a de Polignac number, because none of the positive numbers 2^k-780891221 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 (780891227) 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, 328166 + ... + 330536.

It is an arithmetic number, because the mean of its divisors is an integer number (54081600).

Almost surely, 2^780891221 is an apocalyptic number.

It is an amenable number.

780891221 is a deficient number, since it is larger than the sum of its proper divisors (84414379).

780891221 is a wasteful number, since it uses less digits than its factorization.

780891221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2840.

The product of its (nonzero) digits is 16128, while the sum is 38.

The square root of 780891221 is about 27944.4309478651. The cubic root of 780891221 is about 920.8668660711.

The spelling of 780891221 in words is "seven hundred eighty million, eight hundred ninety-one thousand, two hundred twenty-one".