661642026 has 16 divisors (see below), whose sum is σ = 1326974400. Its totient is φ = 219932288.

The previous prime is 661642019. The next prime is 661642031. The reversal of 661642026 is 620246166.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 151431 + ... + 155738.

It is an arithmetic number, because the mean of its divisors is an integer number (82935900).

Almost surely, 2^661642026 is an apocalyptic number.

661642026 is an abundant number, since it is smaller than the sum of its proper divisors (665332374).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

661642026 is a wasteful number, since it uses less digits than its factorization.

661642026 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 307533.

The product of its (nonzero) digits is 20736, while the sum is 33.

The square root of 661642026 is about 25722.4031925479. The cubic root of 661642026 is about 871.3802137433.

The spelling of 661642026 in words is "six hundred sixty-one million, six hundred forty-two thousand, twenty-six".