1165721900 has 36 divisors (see below), whose sum is σ = 2890992048. Its totient is φ = 399675840.

The previous prime is 1165721849. The next prime is 1165721933. The reversal of 1165721900 is 91275611.

It is a super-2 number, since 2×1165721900² = 2717815096279220000, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 831959 + ... + 833358.

Almost surely, 2^1165721900 is an apocalyptic number.

1165721900 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1165721900 is an abundant number, since it is smaller than the sum of its proper divisors (1725270148).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1165721900 is a wasteful number, since it uses less digits than its factorization.

1165721900 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1665338 (or 1665331 counting only the distinct ones).

The product of its (nonzero) digits is 3780, while the sum is 32.

The square root of 1165721900 is about 34142.6697843036. The cubic root of 1165721900 is about 1052.4423568689.

The spelling of 1165721900 in words is "one billion, one hundred sixty-five million, seven hundred twenty-one thousand, nine hundred".