661610615501 has 16 divisors (see below), whose sum is σ = 723584836800. Its totient is φ = 599942966400.

The previous prime is 661610615473. The next prime is 661610615503. The reversal of 661610615501 is 105516016166.

It is a cyclic number.

It is not a de Polignac number, because 661610615501 - 2¹⁸ = 661610353357 is a prime.

It is a super-2 number, since 2×661610615501² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661610615503) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6891890 + ... + 6987228.

It is an arithmetic number, because the mean of its divisors is an integer number (45224052300).

Almost surely, 2^661610615501 is an apocalyptic number.

It is an amenable number.

661610615501 is a deficient number, since it is larger than the sum of its proper divisors (61974221299).

661610615501 is a wasteful number, since it uses less digits than its factorization.

661610615501 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 96940.

The product of its (nonzero) digits is 32400, while the sum is 38.

The spelling of 661610615501 in words is "six hundred sixty-one billion, six hundred ten million, six hundred fifteen thousand, five hundred one".