661495521201 has 4 divisors (see below), whose sum is σ = 881994028272. Its totient is φ = 440997014132.

The previous prime is 661495521179. The next prime is 661495521257. The reversal of 661495521201 is 102125594166.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 661495521201 - 2¹⁹ = 661494996913 is a prime.

It is not an unprimeable number, because it can be changed into a prime (661495521601) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 110249253531 + ... + 110249253536.

It is an arithmetic number, because the mean of its divisors is an integer number (220498507068).

Almost surely, 2^661495521201 is an apocalyptic number.

It is an amenable number.

661495521201 is a deficient number, since it is larger than the sum of its proper divisors (220498507071).

661495521201 is a wasteful number, since it uses less digits than its factorization.

661495521201 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 220498507070.

The product of its (nonzero) digits is 129600, while the sum is 42.

The spelling of 661495521201 in words is "six hundred sixty-one billion, four hundred ninety-five million, five hundred twenty-one thousand, two hundred one".