731721135649 has 9 divisors (see below), whose sum is σ = 851192776371. Its totient is φ = 627184412400.

The previous prime is 731721135601. The next prime is 731721135659. The reversal of 731721135649 is 946531127137.

The square root of 731721135649 is 855407.

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

It can be written as a sum of positive squares in only one way, i.e., 722171937249 + 9549198400 = 849807^2 + 97720^2 .

It is not a de Polignac number, because 731721135649 - 2²³ = 731712747041 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (49).

It is not an unprimeable number, because it can be changed into a prime (731721135659) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 5926749 + ... + 6048949.

Almost surely, 2^731721135649 is an apocalyptic number.

731721135649 is the 855407-th square number.

731721135649 is the 427704-th centered octagonal number.

It is an amenable number.

731721135649 is a deficient number, since it is larger than the sum of its proper divisors (119471640722).

731721135649 is an frugal number, since it uses more digits than its factorization.

731721135649 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 244416 (or 122208 counting only the distinct ones).

The product of its digits is 952560, while the sum is 49.

Multiplying 731721135649 by its sum of digits (49), we get a square (35854335646801 = 5987849²).

731721135649 divided by its sum of digits (49) gives a square (14933084401 = 122201²).

The spelling of 731721135649 in words is "seven hundred thirty-one billion, seven hundred twenty-one million, one hundred thirty-five thousand, six hundred forty-nine".