642497690 has 8 divisors (see below), whose sum is σ = 1156495860. Its totient is φ = 256999072.

The previous prime is 642497683. The next prime is 642497693. The reversal of 642497690 is 96794246.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 596678329 + 45819361 = 24427^2 + 6769^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a super-2 number, since 2×642497690² = 825606563310672200, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (642497693) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 32124875 + ... + 32124894.

Almost surely, 2^642497690 is an apocalyptic number.

642497690 is a deficient number, since it is larger than the sum of its proper divisors (513998170).

642497690 is a wasteful number, since it uses less digits than its factorization.

642497690 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 64249776.

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

The square root of 642497690 is about 25347.5381447588. The cubic root of 642497690 is about 862.8934853751.

The spelling of 642497690 in words is "six hundred forty-two million, four hundred ninety-seven thousand, six hundred ninety".