61521257405 has 16 divisors (see below), whose sum is σ = 74389719600. Its totient is φ = 48841477632.

The previous prime is 61521257351. The next prime is 61521257429. The reversal of 61521257405 is 50475212516.

It can be written as a sum of positive squares in 8 ways, for example, as 2570388601 + 58950868804 = 50699^2 + 242798^2 .

It is a cyclic number.

It is not a de Polignac number, because 61521257405 - 2⁶ = 61521257341 is a prime.

It is a super-2 number, since 2×61521257405² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 779627 + ... + 854903.

It is an arithmetic number, because the mean of its divisors is an integer number (4649357475).

Almost surely, 2^61521257405 is an apocalyptic number.

It is an amenable number.

61521257405 is a deficient number, since it is larger than the sum of its proper divisors (12868462195).

61521257405 is a wasteful number, since it uses less digits than its factorization.

61521257405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 76528.

The product of its (nonzero) digits is 84000, while the sum is 38.

The spelling of 61521257405 in words is "sixty-one billion, five hundred twenty-one million, two hundred fifty-seven thousand, four hundred five".