991737139600 has 405 divisors, whose sum is σ = 2647546630651. Its totient is φ = 356916224000.

The previous prime is 991737139579. The next prime is 991737139609. The reversal of 991737139600 is 6931737199.

It is a happy number.

The square root of 991737139600 is 995860.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 40 ways, for example, as 517093304464 + 474643835136 = 719092^2 + 688944^2 .

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (991737139609) by changing a digit.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 9819179550 + ... + 9819179650.

Almost surely, 2^991737139600 is an apocalyptic number.

991737139600 is the 995860-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 991737139600

991737139600 is an abundant number, since it is smaller than the sum of its proper divisors (1655809491051).

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

991737139600 is a wasteful number, since it uses less digits than its factorization.

991737139600 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 312 (or 154 counting only the distinct ones).

The product of its (nonzero) digits is 1928934, while the sum is 55.

The spelling of 991737139600 in words is "nine hundred ninety-one billion, seven hundred thirty-seven million, one hundred thirty-nine thousand, six hundred".