61621365640 has 16 divisors (see below), whose sum is σ = 138648072780. Its totient is φ = 24648546240.

The previous prime is 61621365613. The next prime is 61621365671. The reversal of 61621365640 is 4656312616.

It can be written as a sum of positive squares in 2 ways, for example, as 50035426596 + 11585939044 = 223686^2 + 107638^2 .

It is a Harshad number since it is a multiple of its sum of digits (40), and also a Moran number because the ratio is a prime number: 1540534141 = 61621365640 / (6 + 1 + 6 + 2 + 1 + 3 + 6 + 5 + 6 + 4 + 0).

It is a junction number, because it is equal to n+sod(n) for n = 61621365593 and 61621365602.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 770267031 + ... + 770267110.

Almost surely, 2^61621365640 is an apocalyptic number.

It is an amenable number.

61621365640 is an abundant number, since it is smaller than the sum of its proper divisors (77026707140).

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

61621365640 is a wasteful number, since it uses less digits than its factorization.

61621365640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1540534152 (or 1540534148 counting only the distinct ones).

The product of its (nonzero) digits is 155520, while the sum is 40.

The spelling of 61621365640 in words is "sixty-one billion, six hundred twenty-one million, three hundred sixty-five thousand, six hundred forty".