661888641516025 has 48 divisors (see below), whose sum is σ = 1023266520501120. Its totient is φ = 412604344857600.

The previous prime is 661888641516013. The next prime is 661888641516043. The reversal of 661888641516025 is 520615146888166.

It is a happy number.

It is a de Polignac number, because none of the positive numbers 2^k-661888641516025 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 709260027 + ... + 710192623.

It is an arithmetic number, because the mean of its divisors is an integer number (21318052510440).

Almost surely, 2^{661888641516025} is an apocalyptic number.

It is an amenable number.

661888641516025 is a deficient number, since it is larger than the sum of its proper divisors (361377878985095).

661888641516025 is a wasteful number, since it uses less digits than its factorization.

661888641516025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1301314 (or 1301309 counting only the distinct ones).

The product of its (nonzero) digits is 132710400, while the sum is 67.

The spelling of 661888641516025 in words is "six hundred sixty-one trillion, eight hundred eighty-eight billion, six hundred forty-one million, five hundred sixteen thousand, twenty-five".