20697401666 has 4 divisors (see below), whose sum is σ = 31046102502. Its totient is φ = 10348700832.

The previous prime is 20697401663. The next prime is 20697401677. The reversal of 20697401666 is 66610479602.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 16311121225 + 4386280441 = 127715^2 + 66229^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 20697401666.

It is not an unprimeable number, because it can be changed into a prime (20697401663) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5174350415 + ... + 5174350418.

Almost surely, 2^20697401666 is an apocalyptic number.

20697401666 is a deficient number, since it is larger than the sum of its proper divisors (10348700836).

20697401666 is a wasteful number, since it uses less digits than its factorization.

20697401666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10348700835.

The product of its (nonzero) digits is 653184, while the sum is 47.

The spelling of 20697401666 in words is "twenty billion, six hundred ninety-seven million, four hundred one thousand, six hundred sixty-six".