642666051 has 12 divisors (see below), whose sum is σ = 977153320. Its totient is φ = 405894240.

The previous prime is 642666047. The next prime is 642666067. The reversal of 642666051 is 150666246.

It is a happy number.

It is not a de Polignac number, because 642666051 - 2² = 642666047 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 642665997 and 642666015.

It is not an unprimeable number, because it can be changed into a prime (642666001) 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, 1878970 + ... + 1879311.

Almost surely, 2^642666051 is an apocalyptic number.

642666051 is a deficient number, since it is larger than the sum of its proper divisors (334487269).

642666051 is a wasteful number, since it uses less digits than its factorization.

642666051 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3758306 (or 3758303 counting only the distinct ones).

The product of its (nonzero) digits is 51840, while the sum is 36.

The square root of 642666051 is about 25350.8589795297. The cubic root of 642666051 is about 862.9688500675.

The spelling of 642666051 in words is "six hundred forty-two million, six hundred sixty-six thousand, fifty-one".