661920026 has 4 divisors (see below), whose sum is σ = 992880042. Its totient is φ = 330960012.

The previous prime is 661920011. The next prime is 661920037. The reversal of 661920026 is 620029166.

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., 614296225 + 47623801 = 24785^2 + 6901^2 .

It is a junction number, because it is equal to n+sod(n) for n = 661919974 and 661920001.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 165480005 + ... + 165480008.

Almost surely, 2^661920026 is an apocalyptic number.

661920026 is a deficient number, since it is larger than the sum of its proper divisors (330960016).

661920026 is a wasteful number, since it uses less digits than its factorization.

661920026 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 330960015.

The product of its (nonzero) digits is 7776, while the sum is 32.

The square root of 661920026 is about 25727.8064747075. The cubic root of 661920026 is about 871.5022383277.

The spelling of 661920026 in words is "six hundred sixty-one million, nine hundred twenty thousand, twenty-six".