99991057 has 8 divisors (see below), whose sum is σ = 102839400. Its totient is φ = 97150464.

The previous prime is 99991049. The next prime is 99991063. The reversal of 99991057 is 75019999.

It can be written as a sum of positive squares in 4 ways, for example, as 23270976 + 76720081 = 4824^2 + 8759^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 99991057 - 2³ = 99991049 is a prime.

It is a super-2 number, since 2×99991057² = 19996422959954498, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 99991057.

It is not an unprimeable number, because it can be changed into a prime (99991757) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 32919 + ... + 35827.

It is an arithmetic number, because the mean of its divisors is an integer number (12854925).

Almost surely, 2^99991057 is an apocalyptic number.

It is an amenable number.

99991057 is a deficient number, since it is larger than the sum of its proper divisors (2848343).

99991057 is a wasteful number, since it uses less digits than its factorization.

99991057 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3875.

The product of its (nonzero) digits is 229635, while the sum is 49.

The square root of 99991057 is about 9999.5528400024. The cubic root of 99991057 is about 464.1450463725.

The spelling of 99991057 in words is "ninety-nine million, nine hundred ninety-one thousand, fifty-seven".