990881257 has 2 divisors, whose sum is σ = 990881258. Its totient is φ = 990881256.

The previous prime is 990881219. The next prime is 990881267. The reversal of 990881257 is 752188099.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 892157161 + 98724096 = 29869^2 + 9936^2 .

It is a cyclic number.

It is not a de Polignac number, because 990881257 - 2¹⁵ = 990848489 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 990881257.

It is not a weakly prime, because it can be changed into another prime (990881267) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 495440628 + 495440629.

It is an arithmetic number, because the mean of its divisors is an integer number (495440629).

Almost surely, 2^990881257 is an apocalyptic number.

It is an amenable number.

990881257 is a deficient number, since it is larger than the sum of its proper divisors (1).

990881257 is an equidigital number, since it uses as much as digits as its factorization.

990881257 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 362880, while the sum is 49.

The square root of 990881257 is about 31478.2664230418. The cubic root of 990881257 is about 996.9511328561.

The spelling of 990881257 in words is "nine hundred ninety million, eight hundred eighty-one thousand, two hundred fifty-seven".