661769021901 has 12 divisors (see below), whose sum is σ = 955453499808. Its totient is φ = 407242474704.

The previous prime is 661769021897. The next prime is 661769021909. The reversal of 661769021901 is 109120967166.

It is a happy number.

It is not a de Polignac number, because 661769021901 - 2² = 661769021897 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661769021909) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 652631665 + ... + 652632678.

It is an arithmetic number, because the mean of its divisors is an integer number (79621124984).

Almost surely, 2^661769021901 is an apocalyptic number.

It is an amenable number.

661769021901 is a deficient number, since it is larger than the sum of its proper divisors (293684477907).

661769021901 is a wasteful number, since it uses less digits than its factorization.

661769021901 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1305264372 (or 1305264359 counting only the distinct ones).

The product of its (nonzero) digits is 244944, while the sum is 48.

The spelling of 661769021901 in words is "six hundred sixty-one billion, seven hundred sixty-nine million, twenty-one thousand, nine hundred one".