891663890 has 16 divisors (see below), whose sum is σ = 1728456408. Its totient is φ = 329229696.

The previous prime is 891663853. The next prime is 891663911. The reversal of 891663890 is 98366198.

It can be written as a sum of positive squares in 4 ways, for example, as 425060689 + 466603201 = 20617^2 + 21601^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3429347 + ... + 3429606.

Almost surely, 2^891663890 is an apocalyptic number.

891663890 is a deficient number, since it is larger than the sum of its proper divisors (836792518).

891663890 is a wasteful number, since it uses less digits than its factorization.

891663890 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6858973.

The product of its (nonzero) digits is 559872, while the sum is 50.

The square root of 891663890 is about 29860.7416183858. The cubic root of 891663890 is about 962.4992351711.

The spelling of 891663890 in words is "eight hundred ninety-one million, six hundred sixty-three thousand, eight hundred ninety".