990887178551 has 2 divisors, whose sum is σ = 990887178552. Its totient is φ = 990887178550.

The previous prime is 990887178529. The next prime is 990887178583. The reversal of 990887178551 is 155871788099.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 990887178551 - 2⁶ = 990887178487 is a prime.

It is a super-2 number, since 2×990887178551² (a number of 25 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (990887178521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 495443589275 + 495443589276.

It is an arithmetic number, because the mean of its divisors is an integer number (495443589276).

Almost surely, 2^990887178551 is an apocalyptic number.

990887178551 is a deficient number, since it is larger than the sum of its proper divisors (1).

990887178551 is an equidigital number, since it uses as much as digits as its factorization.

990887178551 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 50803200, while the sum is 68.

The spelling of 990887178551 in words is "nine hundred ninety billion, eight hundred eighty-seven million, one hundred seventy-eight thousand, five hundred fifty-one".